Apparatus and Methods for Determining Line of Sight (LOS) from Intensity Measurements

ABSTRACT

A method performed by a first device includes communicating, by the first device, with a second device, a line of sight (LOS) determination request including a LOS indicator indicating that a LOS procedure is used in LOS characterization of a transmission between the first device and the second device; transmitting, by the second device, a first set of reference signals, via a first plurality of transmitting resources; and measuring, by the first device, a second set of reference signals, transmitted by the second device, via a second plurality of receiving resources. This method comprises of both embodiments when there is LOS characterization transmission between the first device and the second device, and when there is no LOS characterization transmission between the first device and the second device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/US2021/055068, filed on Oct. 14, 2021, entitled “Apparatus andMethods for Determining Line of Sight (LOS) from IntensityMeasurements,” which claims the benefit of U.S. Provisional PatentApplication No. 63/092,261, filed Oct. 15, 2020, entitled “Apparatus andMethods for Determining Line of Sight (LOS) from Polarization IntensityMeasurements,” all of which are hereby incorporated herein by referencein its entireties.

TECHNICAL FIELD

The present disclosure relates generally to a system and method fordigital communications, and, in particular embodiments, to a system andmethod for determining line of sight (LOS).

BACKGROUND

A time of flight (ToF) is used in many applications to estimate thedistance between a transmitter and a receiver. The ToF is defined as aduration of propagation of a wave signal between the transmitter and thereceiver. One way to estimate ToF is based on exchanging multiple frameswith time stamps between the transmitter and the receiver. When the ToFis determined, a simple multiplication with the speed of light providesan estimation of the distance between transmitter and the receiver. Oncethe distance from an unknown location to at least three fixed points(with known coordinates) is determined, a simple triangulation(multi-lateration) algorithm could be used to obtain the location of theunknown point.

When the line of sight (LOS) path between transmitter and receiver isnot available and the communication is only non-line of sight (NLOS),several copies of the transmitted signal are received due toreflections, where each copy of the signal corresponds to a differentpath of the propagation between transmitter and receiver and thereforehas a different ToF. In the case of NLOS, the ToF for each pathcorresponds to the length of the path rather than to the geometricdistance between the transmitter and the receiver. In this case, thepath length based on the ToF is obviously larger than the actualdistance between the transmitter and the receiver, which in turn leadsto error in the estimation of the location.

Therefore, there is a need to know if the signal propagation for atransmission (or a copy of it) corresponds to the LOS propagation inorder to determine the exact distance between the transmitter and thereceiver.

When the location estimation is performed at the transmitter (i.e.network), the knowledge when the signal corresponds to a LOS propagationis needed to be conveyed by the receiver to the transmitter.Alternatively, if the location estimation is performed at the receiver(i.e. handset), the knowledge when the signal corresponds to a LOSpropagation would not need to be conveyed by the receiver to thetransmitter.

SUMMARY

According to a first aspect, a method performed by a first device isprovided. The method includes receiving, by the first device from asecond device, an indicator of Line of Sight/Non Line of Sight(LoS/NLoS) feature support, and based thereon, communicating, by thefirst device, with the second device, a line of sight (LOS)determination request including a LOS indicator indicating that a LOSprocedure is used in LOS characterization of a transmission between thefirst device and the second device; receiving, by the first device fromthe second device, a first set of reference signals via a firstplurality of transmitting resources; and measuring, by the first device,the first set of reference signals, transmitted by the second device,via a second plurality of receiving resources.

In a first implementation form of the method according to the firstaspect as such, the LOS indicator is a binary indicator indicating thatthe LOS characterization is LOS or NLOS.

In a second implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the LOS indicator is a multiple level soft indicator indicating thelikelihood or confidence to which the LOS characterization is LOS orNLOS.

In a third implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the first set of reference signals further comprises: receiving eachreference signal in the first set of references signals separately oneach receiving resource; and identifying, by the first device, via asearch procedure, each reference signal corresponding to each receivingresource.

In a fourth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the search procedure comprises a maximal correlation receiver over allpossible reference signals.

In a fifth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,measuring, by the first device, the first set of reference signalsfurther comprises: measuring, by the first device, a plurality ofchannel estimations on each receiving resource, by correlating with thecorresponding reference signal; determining, by the first device, afirst arrival path of each channel estimation; and measuring, by thefirst device, a reference signal received power (RSRP) on the firstarrival path for each channel estimation.

In a sixth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the method further comprises transmitting, by the first device, to thesecond device, the RSRPs of measured reference signals via eachresource.

In a seventh implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the method further comprises: determining, by the first device, that thevalue of a given metric, determined from the RSRP measurements of eachreference signal on each resource, does meet a specified threshold, andbased thereon, determining, by the first device, that the LOScharacterization of the transmission comprises a LOS transmission.

In an eighth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the method further comprises, determining, by the first device, that thevalue of a given metric, determined from the RSRP measurements of eachreference signal via each resource, does not meet a specified threshold,and based thereon, determining, by the first device, that the LOScharacterization of the transmission comprises a non-LOS (NLOS)transmission.

In a ninth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the method further comprises transmitting, by the first device, the LOScharacterization of the transmission.

In a tenth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the method further comprises receiving, by the first device, from thesecond device, a LOS characterization of the transmission.

In an eleventh implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,measuring the plurality of reference signals comprises measuring areference signal received power (RSRP) value or a reference signalreceived quality (RSRQ) value.

In a twelfth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,communicating the LOS determination request comprises transmitting theLOS determination request or receiving the LOS determination request.

In a thirteenth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the first device comprises a user equipment (UE), and the second devicecomprises an access node.

In a fourteenth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the LOS determination request further comprises a measurement gapspecifying a location of the first and second resources.

In a fifteenth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the LOS determination request further comprises a first measurement gapspecifying a location of the first resource, and a second measurementgap specifying a location of the second resource.

In a sixteenth implementation form of the method according to the firstaspect as such or any preceding implementation form of the first aspect,the reference signals are transmitted sequentially in time, one afterthe other.

According to a second aspect, a first device is provided. The firstdevice includes a non-transitory memory storage comprising instructions,and one or more processors in communication with the memory storage. Theone or more processors execute the instructions to: receive, from asecond device, an indicator of Line of Sight/Non Line of Sight(LoS/NLoS) feature support, and based thereon communicate, with thesecond device, a line of sight (LOS) determination request including aLOS indicator indicating that a LOS procedure is used in LOScharacterization of a transmission between the first device and thesecond device; measure a first signal on a first resource of a channel;and measure a second signal on a second resource of the channel, withthe first and second signals being multiplexed in a frequency domain ora code domain.

In a first implementation form of the first device according to thesecond aspect as such, the LOS indicator is a binary indicatorindicating that the LOS characterization is LOS or NLOS.

In a second implementation form of the first device according to thesecond aspect as such or any preceding implementation form of the secondaspect, the LOS indicator is a multiple level soft indicator indicatingthe likelihood or confidence to which the LOS characterization is LOS orNLOS.

In a third implementation form of the first device according to thesecond aspect as such or any preceding implementation form of the secondaspect, the one or more processors further execute the instructions totransmit, to the second device, a measurement of the first signal and ameasurement of the second signal.

In a fourth implementation form of the first device according to thesecond aspect as such or any preceding implementation form of the secondaspect, the one or more processors further execute the instructions toreceive, from the second device, the LOS characterization of thetransmission.

In a fifth implementation form of the first device according to thesecond aspect as such or any preceding implementation form of the secondaspect, the one or more processors further execute the instructions todetermine that a difference between a measurement of the first signaland a measurement of the second signal meets a specified threshold, andbased thereon determine that the LOS characterization of thetransmission comprises a LOS transmission.

In a sixth implementation form of the first device according to thesecond aspect as such or any preceding implementation form of the secondaspect, the one or more processors further execute the instructions todetermine a difference between a measurement of the first signal and ameasurement of the second signal does not meet a specified threshold,and based thereon determine that the LOS characterization of thetransmission comprises a non-LOS (NLOS) transmission.

In a seventh implementation form of the first device according to thesecond aspect as such or any preceding implementation form of the secondaspect, the one or more processors further execute the instructions totransmit the LOS characterization of the transmission.

In an eighth implementation form of the first device according to thesecond aspect as such or any preceding implementation form of the secondaspect, the one or more processors further execute the instructions totransmit the LOS determination request or receive the LOS determinationrequest.

According to a third aspect, a first device is provided. The firstdevice includes a non-transitory memory storage comprising instructions,and one or more processors in communication with the memory storage. Theone or more processors execute the instructions to: receive, from asecond device, an indicator of Line of Sight/Non Line of Sight(LoS/NLoS) feature support, and based thereon communicate, with a seconddevice, a line of sight (LOS) determination request including a LOSindicator indicating that a LOS procedure is used in LOScharacterization of a transmission between the first device and thesecond device; transmit a first signal on a first resource of a channel;and transmit a second signal on a second resource of the channel, withthe first and second signals being multiplexed in a frequency domain ora code domain.

In a first implementation form of the first device according to thethird aspect as such, the LOS indicator is a binary indicator indicatingthat the LOS characterization is LOS or NLOS.

In a second implementation form of the first device according to thethird aspect as such or any preceding implementation form of the thirdaspect, the LOS indicator is a multiple level soft indicator indicatingthe likelihood or confidence to which the LOS characterization is LOS orNLOS.

In a third implementation form of the first device according to thethird aspect as such or any preceding implementation form of the thirdaspect, the one or more processors further execute the instructions toreceive, from the second device, a LOS characterization of the channel.

In a fourth implementation form of the first device according to thethird aspect as such or any preceding implementation form of the thirdaspect, the one or more processors further execute the instructions toreceive, from the second device, a measurement of the first signal and ameasurement of the second signal.

In a fifth implementation form of the first device according to thethird aspect as such or any preceding implementation form of the thirdaspect, the one or more processors further execute the instructions todetermine that a difference between the measurement of the first signaland the measurement of the second signal meets a specified threshold,and based thereon, further execute the instructions to determine thatthe LOS characterization of the transmission comprises a LOStransmission.

In a sixth implementation form of the first device according to thethird aspect as such or any preceding implementation form of the thirdaspect, the one or more processors further execute the instructions totransmit the LOS characterization of the transmission.

In a seventh implementation form of the first device according to thethird aspect as such or any preceding implementation form of the thirdaspect, the one or more processors further execute the instructions todetermine that a difference between the measurement of the first signaland the measurement of the second signal does not meet a specifiedthreshold, and based thereon, further execute the instructions todetermine that the LOS characterization of the transmission comprises anon-LOS (NLOS) transmission.

In an eighth implementation form of the first device according to thethird aspect as such or any preceding implementation form of the thirdaspect, the one or more processors further execute the instructions totransmit the LOS characterization of the transmission.

An advantage of an example embodiment is that the ranging and thepositioning accuracy of devices in a communications network is increasedby correctly selecting LOS reference signals in order to estimate thedistance between the devices. In addition, once the distance betweentransmitter and receiver is determined the location may be determinedvia triangulation algorithms.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a network for communicating data;

FIG. 2A illustrates an example a communication system in the case ofwhich the propagation via 212 and 212 between transmitter and receiveris as NLOS propagation;

FIG. 2B illustrates an example a communication system in the case ofwhich the propagation via 235 between transmitter and receiver ischaracterized as the LOS propagation (or NLOS beam, NLOS ray, NLOS path,etc.) that may be used for implementing the devices and methodsdisclosed herein;

FIG. 3A illustrates an example of an electromagnetic wave that islinearly polarized;

FIG. 3B illustrates an example of an electromagnetic wave that iscircular polarized;

FIGS. 3C and 3D illustrate examples of an electromagnetic wave 305during a reflection;

FIG. 4A illustrate example of a signal flow diagram of a first exampleembodiment of method for determining LOS according to exampleembodiments presented herein;

FIG. 4B illustrate example of an alternate signal flow diagram of afirst example embodiment of method for determining LOS according toexample embodiments presented herein;

FIG. 4C illustrate example of another alternate signal flow diagram of afirst example embodiment of method for determining LOS according toexample embodiments presented herein;

FIG. 5 illustrate example of a communication system in the case of whichthe propagation between transmitter and receiver is NLOS with acylindrical reflection surface that obstructs LOS communication (e.g.,beam) with a cylindrical reflection region according to exampleembodiments presented herein;

FIG. 6A illustrate example of a signal flow diagram of a second exampleembodiment of method for determining the LOS according to exampleembodiments presented herein;

FIG. 6B illustrate example of an alternate signal flow diagram of asecond example embodiment of method for determining LOS according toexample embodiments presented herein;

FIG. 7 illustrates an example of a signal flow diagram of a thirdexample embodiment of method for determining LOS according to exampleembodiments presented herein;

FIG. 8A illustrates a flowchart of an example method for UE operationsin a UE-centric solution according to example embodiments presentedherein;

FIG. 8B illustrates a flowchart of an example method for gNB operationsin a UE-centric solution according to example embodiments presentedherein;

FIG. 9A illustrates a flowchart of an example method for UE operation ina gNB-centric solution according to example embodiments presentedherein;

FIG. 9B illustrates a flowchart of an example method for gNB operationin a gNB-centric solution according to example embodiments presentedherein;

FIG. 10 illustrates a flow diagram of example operations occurring in aUE in a UE-centric LOS measurements solution according to exampleembodiments presented herein;

FIG. 11 illustrates a flow diagram of example operations occurring in agNB in a UE-centric LOS measurements solution according to exampleembodiments presented herein;

FIG. 12 illustrates an example communication system according to exampleembodiments presented herein;

FIGS. 13A and 13B illustrate example devices that may implement themethods and teachings according to this disclosure;

FIG. 14 is a block diagram of a computing system that may be used forimplementing the devices and methods disclosed herein;

FIG. 15 illustrates a block diagram of an example embodiment processingsystem for performing methods described herein;

FIG. 16 illustrates a block diagram of a transceiver adapted to transmitand receive signaling over a telecommunications network according toexample embodiments presented herein;

FIGS. 17A and 17B illustrate the polarization orientations between a gNBand a UE in a LOS path propagation, by transmitting and receiving withantenna-beams having two orthogonal polarizations according to exampleembodiments presented herein;

FIGS. 18A-18C illustrate the received and transmitted field-vectors inthe LCS of the receiver arriving from a given spherical directionaccording to example embodiments presented herein;

FIGS. 19A-19B illustrate a polarization-LOS scheme for N differentfield-vectors each with a distinct polarization orientation, received byan antenna-resource with single polarization orientation according toexample embodiments presented herein;

FIGS. 20A-20C illustrate a polarization-LOS scheme for 4 differentfield-vectors each with a distinct polarization orientation, received byan antenna-resource with single polarization orientation according toexample embodiments presented herein;

FIG. 20D illustrates a polarization-LOS scheme for 3 differentfield-vectors each with a distinct polarization orientation, received byan antenna-resource with single polarization orientation according toexample embodiments presented herein;

FIG. 20E illustrates a polarization-LOS scheme in a situation where thetransmitter transmits in more than S>4 different polarizationorientations according to example embodiments presented herein;

FIG. 21A illustrates a block diagram for requesting and performing aPolarization-LOS measurement and a binary decision, which is reportedback to the transmitter according to example embodiments presentedherein;

FIG. 21B illustrates a block diagram for requesting and performing aPolarization-LOS measurement which is reported back to the transmitteraccording to example embodiments presented herein; and

FIG. 22 illustrates a block diagram for the UE performing LOSdetermination on its own according to example embodiments presentedherein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration specific example embodiments which may be practiced. Theseexample embodiments are described in sufficient detail to enable thoseskilled in the art to practice the disclosure, and it is to beunderstood that other example embodiments may be utilized and thatstructural, logical and electrical changes may be made without departingfrom the scope of the present disclosure. The following description ofexample embodiments is, therefore, not to be taken in a limited sense,and the scope of the present disclosure is defined by the appendedclaims.

The making and using of embodiments of this disclosure are discussed indetail below. It should be appreciated, however, that the conceptsdisclosed herein can be embodied in a wide variety of specific contexts,and that the specific example embodiments discussed herein are merelyillustrative and do not serve to limit the scope of the claims. Further,it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of this disclosure as defined by the appended claims. While theinventive aspects are described primarily in the context of 5G wirelessnetworks, it should also be appreciated that those inventive aspects mayalso be applicable to 4G and 3G wireless networks.

The functions or algorithms described herein may be implemented insoftware in one example embodiment. The software may consist of computerexecutable instructions stored on computer readable media or computerreadable storage device such as one or more non-transitory memories orother type of hardware based storage devices, either local or networked.Further, such functions correspond to modules, which may be software,hardware, firmware or any combination thereof. Multiple functions may beperformed in one or more modules as desired, and the example embodimentsdescribed are merely examples. The software may be executed on a digitalsignal processor, ASIC, microprocessor, or other type of processoroperating on a computer system, such as a personal computer, server orother computer system, turning such computer system into a specificallyprogrammed machine.

FIG. 1 illustrates a network 100 for communicating data. The network 100comprises an access node 110 having a coverage area 112, a plurality ofuser equipments (UEs) 120, 121, and a backhaul network 130. As shown,the base station 110 establishes uplink (dashed line) or downlink (solidline) connections with the UEs 120, 121, which serve to carry wirelesstransmission from the UEs 120, 121 to the base station 110 andvice-versa. Wireless transmission over the uplink or downlinkconnections may include data communicated between the UEs 120, 121, aswell as data communicated to or from a remote-end (not shown) by way ofthe backhaul network 130. As used herein, the term access node refers toany component (or collection of components) configured to providewireless access to a network, such as base station, next generation basestation (gNB), an E-UTRAN base station (eNB), a macro-cell, a femtocell,a Wi-Fi access point (AP), or other wirelessly enabled devices. Accessnodes may provide wireless access in accordance with one or morewireless communication protocols, e.g., the Third Generation PartnershipProject (3GPP) long term evolution (LTE), LTE advanced (LTE-A), 5G, 5GLTE, 5G NR, High Speed Packet Access (HSPA), Wi-Fi802.11a/b/g/n/ac/ad/ax/ay/be, etc. As used herein, the term “UE” refersto any component (or collection of components) capable of establishing awireless connection with a base station, such as a mobile device, amobile station (STA), an IoT device (e.g., a smart sensor, etc.),subscribers, stations, and other wirelessly enabled devices. In someexample embodiments, the network 100 may comprise various other wirelessdevices, such as relays, low power nodes, etc.

When the direct or line of sight (LOS) path between a transmitter and areceiver is blocked, the propagation between transmitter and receiver ispossible through a non-line of sight (NLOS) path. In other words thesignal propagation is through the reflections and diffractions.

FIG. 2A illustrates an example a communication system 200 in the case ofwhich the propagation between transmitter 202 and receiver 204 is asNLOS propagation. Communication system 200 that may be used forimplementing the devices and methods disclosed herein. The system 200may implement one or more channel access methods, including, but notlimited to, methods such as code division multiple access (CDMA), timedivision multiple access (TDMA), frequency division multiple access(FDMA), orthogonal FDMA (OFDMA), or single-carrier FDMA (SC-FDMA).

In this example, the communication system 200 includes a transmitter 202and a receiver 204. While certain numbers of these components orelements are shown in FIG. 2A, any number of these components orelements may be included in the system 200. In FIG. 2A, both thetransmitter 202 and the receiver 204 may transmit and receiveelectromagnetic waves under multiple polarizations. And the transmitter202 and the receiver 204 may be any entity capable of sending andreceiving, including a base station, a mobile terminal, an access point,a wireless local area network (WLAN) station, etc.

The transmitter 202 may transmit repeatedly a reference signals aselectromagnetic (EM) waves with different polarizations (for instancevertical polarization, horizontal polarization, and 45 degreespolarization) to the receiver 204. The receiver 204 may receive thesignal transmitted by the transmitter 202. For multi-path propagation,each path corresponds to one copy of the same transmission (which meanseach path corresponds to at least one reflection), such as the copies of210 and 212 in FIG. 2A. In the case of the propagation between thetransmitter 202 and the receiver 204 being characterized as NLOSpropagation (or NLOS beam, NLOS ray, etc.), a blockage 208 is locatedbetween the transmitter 202 and the receiver 204. The signal copy willnot pass the blockage 208, such as the signal copy 210 being blocked bythe blockage 208. A blockage is defined by any obstacle which willattenuate the electromagnetic (EM) wave below a given noise-floor. Ifthe line-of-sight path is blocked by some other dispersive medium, suchas water, the delay of the EM wave can be larger than the sampling ratetimes the speed of light in vacuum. In this case the propagation via LOSpath is delayed, which will lead to an overestimate of the distance forTOA based position techniques. A reflector 206 may also be includedbetween the transmitter 202 and the receiver 204. The signal copy, suchas the signal copy 212 may be reflected by the reflector 206, and thencontinue to the receiver 204. The blockage 208 may block the signal sentto the receiver 204. In this example, for each transmission, thereceiver 204 receives one or more copies of the same signal thatpropagates on different paths, with none of them corresponding to anunobstructed (direct or LOS) path. Therefore, the communication betweenthe transmitter 202 and receiver 204 is NLOS communication.

FIG. 2B illustrates an example a communication system 230 in the case ofwhich the propagation between transmitter 202 and receiver 204 ischaracterized as the LOS propagation (or NLOS beam, NLOS ray, etc.) thatmay be used for implementing the devices and methods disclosed herein.In this case, no blockage is located between the transmitter 202 and thereceiver 204, and there is an unobstructed direct path 230 between thetransmitter 202 and the receiver 204 allowing for the signal on path 230to be unobstructed. Therefore, the communication between the transmitter202 and receiver 204 is LOS communication.

The transmitter 202 in the disclosure is a device, such as an accessnode, a base station, a mobile terminal, an access point, a WLANstation, a UE, and so on, which transmits signals to the receiver 204 incertain examples. And the receiver 204 in the disclosure is a device,such as an access node, a base station, a mobile terminal, an accesspoint, a WLAN station, a UE, and so on, which receives signals from thetransmitter 202 in certain examples. In any example, the function oftransmitter 202 and function of receiver 204 may be exchanged.

FIG. 3A illustrates an example of an electromagnetic wave 302 that islinearly polarized. In this example, a signal wave, such as theelectromagnetic wave 302, is linear polarized (for example in “z”direction of FIG. 3A) if the electric field vector E oscillates in asingle fixed plane, in the “z” direction in this example. In FIG. 3A,“E” represents the vector of electric field 302 of the signal wave, “B”represents the vector of magnetic field 306 of the signal wave, and “c”represents the speed of propagation of the electromagnetic wave,depending on the medium it propagates. The signal wave in the FIG. 3A islinearly polarized because “E” oscillates only in the plane (x-z), andsignal wave (such as an electromagnetic wave) is the combination of thetwo vectors oscillations (such as the magnetic field B and the electricfield E). The polarization orientation (phasor) of a linear polarizedwave can be then described by an angle in the (z-y) phasor-plane 304,measured from the z-axis. In the example of FIG. 3A, the angle is 0°,and the polarization is Vertical polarized, i.e., along the z-axis ofthe propagation.

FIG. 3B illustrates an example of an electromagnetic wave 304 that iscircular polarized. In FIG. 3B, the electric intensity vector ofelectromagnetic wave 304 is rotates 360 degrees during a period (e.g.,period 306), which is the minimum time interval for a 360 degreerotation.

FIGS. 3C and 3D illustrate examples of an electromagnetic wave 305during a reflection. Electromagnetic wave 305 is polarized. Whenreflected, a polarized wave (e.g., electromagnetic wave 305) undergoes achange in polarization, while a polarized wave that is not reflectedwill not undergo such changes. As shown in FIG. 3C, a reflectioncoefficient for light which has electric field parallel to a plane ofincidence goes to zero at angle between 0° and 90°. The reflected lightat that angle is linearly polarized, with its electric field vectorsperpendicular to the plane of incidence and parallel to the plane of thesurface from which it is reflecting. The angle at which this occurs isreferred to as the polarizing angle or the Brewster angle. At otherangles, the reflected light is partially polarized. Depending on thesurface and property of the object, the scattered EM wave will have adifferent polarization orientation and intensity as the impeding EMwave.

From Fresnel's equations, it can be determined that the parallelreflection coefficient 320 is zero when the sum of the incident andtransmitted angles is equal to 90°. The application of Snell's lawyields an expression for the Brewster angle. FIG. 3C illustrates anexample where the reflection coefficients are different for wavesparallel and perpendicular to the plane of incidence. FIG. 3C furtherillustrates that when light is incident at the Brewster angle, thereflected light is linearly polarized because the reflection for theparallel component is 0. FIG. 3D illustrates the reflected intensity forrays parallel (parallel reflection coefficient 320) and perpendicular(perpendicular reflection coefficient 325) to the plane of incidence.

In the following description the transmitter and the receiver denotesdevices that may transmit and receive electromagnetic waves withmultiple polarizations. Examples of such transmitters and receivers arebase stations, mobile user devices, access points, WLAN stations, UEs,etc. One example embodiment of proposed solution consists of followingbasic procedure: (1) the transmitter and the receiver acknowledge eachother that they support the feature of LOS determination. For instancethey could exchange messages, or perform a broadcast of messages thatcontain a field indicating the support for the feature; (2) the receiverrequests the transmitter to start the procedure of LOS determination. Inthis request the receiver might indicate the number of transmissions,and the polarizations; (3) the transmitter sends successively(repetitions) during a single transmission or in separate transmissions,reference signals (RS), which allow the receiver to estimate the channelimpulse response. The RS are generally given by a certain bit sequence,encoded in frequency or time domain. The sequence is then modulated atgiven bandwidth on a carrier-frequency, which forms the electromagneticwaveform (radio signal). The RS bit sequence can contain additionalinformation such as Cell-Identification (ID), Beam-ID, orpolarization-ID. The set of possible RSs (RS resource set) must be knownat the receiver. For instance, in the case when there is a singletransmission, the data transmitted consist of multiple repetitions intime of the reference signals, with each repetition at differentpolarization but with same power. When there are multiple transmissions,each transmission is sent at a different polarization. In one exampleembodiment the transmitter indicates in the preamble of itstransmission, the number of repetitions and the polarizationscorresponding to each repetition; (4) the receiver determines the RS andestimates the CIR from each antenna port which corresponds to adifferent polarization orientation. There might be multiplepolarization-ports at the receiver available. From the estimate CIRs thereceiver selects the intensity of the first arrival path correspondingto each received RS and port. In one embodiment, these positiveintensity numbers will be reported back to the transmitter or network.In a second embodiment, the receiver calculates a decision value from agiven metric, depending on the number or transmit and receivedpolarizations. Depending on a given threshold, the receiver can thendecide if the first-path corresponds to a LOS or NLOS path. (5) In oneembodiment, the metric can be given by the difference of thepolarization intensities. If the intensity of first received path ofeach received repetition is invariant to the transmitted polarizationthe receiver concludes that the communication was LOS; (6) the receivermight inform the transmitter that the communication is LOS.

In a different example embodiment the transmitter may broadcast anindication of the LOS feature support, and then indicates the number ofrepetitions and the corresponding polarization for each repetitionfollowed by a broadcast of reference signals at different polarizations.The receivers could then compare the intensity of the first receivedpath at different polarization to determine if the communication is LOS.Transmission of a different polarization orientation could be achievedin different ways such as with two antennas having a similar antennapattern, which have polarizations orthogonal to each other, for examplewith one antenna-polarization parallel with the surface of earth and oneperpendicular. By transmitting the same signal at the same time withdifferent powers over both antennas, any linear polarization orientationcan be radiated. Assuming the RS are normalized in power, the powerweights w_1 and w_2 for antenna 1 and antenna 2 have to satisfyw_1{circumflex over ( )}2+2_2{circumflex over ( )}2=1, to ensure anormalized transmitted RS as the superposition of the two radiated RSs.

In this example, one transceiver transmits reference signals at leasttwice under different polarizations (e.g., the bit sequences haveorthogonal polarizations) and another transceiver receives thesetransmissions and determine the intensity for each of the received waveor each of the received bit sequence repetitions. If the two receivedwaves (or signals) have the same intensity the transceiver concludesthat the propagation of the received waves are LOS. In some exampleembodiments, the transmission of the RSs is sequentially in time (i.e.,one after other). In some instances, repetitions are performed atapproximately the same power, or at powers (known at the receiver) suchthat the receiver may compare the received intensity (power) of eachtransmission to determine if they underwent any reflection.

A multipath channel of communication is a channel where for eachtransmission from the transmitter, the receiver receives multiple copiesof the transmission because the propagation between the transmitter andthe receiver occurs via simultaneous paths. In the real world, each pathcorresponds to one or multiple reflections of the electromagnetic wave.Therefore, in the case of multipath channel propagation, for eachtransmission from the transmitter, the receiver might receive multiplecopies of the same RS (due to the reflections in the environment). Inmany instances, with the LOS communication there is a single path (theshortest path) corresponding to the LOS, and multiple additional pathscorresponding to the reflections. However if the communication is NLOS,all of the paths correspond to reflections (even the shortest) and thereis no LOS path. Therefore in the proposed solution, the receiver has toobserve (only, at least) the intensity of the first arrival path(corresponding to the transmission with the shortest ToF) for each ofpolarization. The receiver retains the intensity of the first arrivalpath (a copy) from the transmissions with different polarizations. Ifthe first received path intensity is invariant for the transmittedpolarizations, i.e., the first received path for each differentpolarization has the same intensity for different transmitterpolarizations, the transmitter and the receiver are in LOS. Paths mayalso be referred to as rays.

In the above method, it is possible that if only one repetition of thebit sequence (two copies total, including the original transmission ofthe bit sequence) are transmitted, a corner case (a very unlikely event)might occur when there is no LOS (NLOS) but under multiple reflections,two transmitted bit sequences with different polarizations are stillreceived with the same intensity. Such a case occurs when the reflectorsare orthogonal with respect to each other, such as, when each reflectoris at 45 degrees to each incident wave.

To deal with this particular case in the proposed solution, thetransmitter sends several repetitions of the same bit sequence underdifferent polarizations (e.g., more than two, so there are at leastthree transmissions) and the receiver determines the received intensityof the first received path (ray) of each transmission. If theseintensities are the same it implies that the received waves were LOS,i.e., the transmissions did not suffer reflections.

FIG. 4A illustrate example of a signal flow diagram 400 of a firstexample embodiment of method for determining LOS, according to thedisclosure. The method may be performed in the context of the system asillustrated in FIG. 2A or in FIG. 2B, and may use the linear polarizedor the circular polarized as an example as illustrated in FIG. 3A or 3B.

In step 402, the receiver 204 requests the transmitter 202 to start theprocedure of LOS determination via sending a LOS determination requestto the transmitter 202. The LOS determination request may include one ormore of a number of transmissions to the receiver 204, and a number ofpolarizations available at the receiver 204. The number of transmissionsto the receiver 204, and the number and the directions of polarizationsof the receiver 204 may also be pre-established via a known definitionof the protocol or standard.

In step 404 the transmitter 202 sends successively, during a singleframe transmission or in separate frames transmissions, a sequence ofreference signals (RSs) with equal-power, where each RS will betransmitted over one of a plurality of antenna-resources. Anantenna-resource can be a certain beam direction or a certainpolarization, such as a linear polarization orientation. For a LOSdetection via polarization measurements, at least two RSs need to betransmitted sequentially in time over two different polarizationorientations. It is understood that the transmission could be inresponse to a prior request (such as the request in step 402) sent bythe receiver 204 to the transmitter 202. Such prior request (such as therequest in step 402) may contain the number and the directions ofpolarizations to be sent by the transmitter 202. The transmission atdifferent polarizations could be achieved in different ways, such as twodipole antennas oriented orthogonally to each other, for example.

For a single frame transmission, the data transmitted by the transmitter202 comprises multiple repetitions (or copies) of the same sequence ofbits, with each repetition corresponding to one polarization of thedifferent polarizations. The number of repetitions may be referred to asthe number of polarizations in the LOS determination request, or may bereferred to as a predefined number agreed between the receiver 204 andthe transmitter 202. For multiple frame transmissions, each frametransmission is sent at different polarization. In one exampleembodiment, the transmitter 204 indicates, for instance in the preambleof its transmission (first part of the transmission), the number of bitsequence repetitions and the polarizations corresponding to each bitsequence repetition that will follow in the transmission.

It is further understood that in some example embodiments of step 404,the transmitter 202 transmits the same signal wave or the same bitsequence at least twice with different polarizations at the same powerand to same direction (the same orientation).

The number of times the same signal wave or the same sequence bit issent may be referred to as the number of transmissions. The number oftransmissions in LOS determination request may specify the number oftimes the same signal wave or the same sequence bit is sent.

In step 406, the receiver 204 checks to determine if the first receivedcopy from each of the plurality of polarizations has been detected andmeasures the power or intensity thereof.

In the example of NLOS multi-path channel propagation, each pathcorresponds to one copy (also referred to as one reflection) of thetransmitted signal wave. The receiver 204 receives multiple copies foreach transmission because the propagation between the transmitter 202and the receiver 204 occurs through multiple paths. In some examples,each path corresponds to one or multiple reflections of theelectromagnetic wave. Therefore, in the case of multipath channelpropagation, for each transmission from the transmitter 202, thereceiver 204 may receive multiple copies of the transmission (due to thereflections in the environment). For the LOS communication, the firstreceived path (which is also the shortest path) corresponds to the LOScommunication, while the other multiple adjacent paths correspond to thereflections.

After the receiver 204 measures (or detects) the first received path(through the received signal) for each transmission, the receiver 204obtains and compares the intensity of each first received copy for theplurality of transmissions, where the first received copy is thereceived copy via the first received path.

For example, the transmitter 202 sends the same bit sequence for twotimes, each time with two polarizations. The two times corresponds totwo transmissions. The first transmission of the same bit sequence withtwo polarizations (polarization A and polarization B, for example), andthe second transmission of the same bit sequence with two polarizations(polarization C and polarization D, for example). The receiver 204 maydetect a first path for the first transmission over a path of thepolarization A and a path of the polarization B. The receiver 204 maydetect a first path for the second transmission over a path of thepolarization C and a path of the polarization D. As an example, thefirst path for the first transmission is the path of the polarization A,and the first path for the second transmission is the path of thepolarization C.

In steps 408 and 410, the receiver 204 determines whether theintensities (or the powers) of each first received copy are equal. Ifthe intensities (or the power) of each first received copy of theplurality of transmissions for each polarization are equal (or less thana threshold value), the transmission between the receiver 204 and thetransmitter 202 may be LOS, and otherwise the transmission between thereceiver 204 and the transmitter 202 is NLOS.

For example, referencing the example presented above, the receiver 204determines whether the intensities of the polarization A and thepolarization C are equal, and characterizes the path in accordancetherewith.

For the signal wave transmitted with circular polarization case (such asthe example represented in FIG. 3B), the received wave signal has thesame intensity during a complete rotation of the vector “E” for LOSwaves. While for NLOS reflections, there is a variation of the intensitydepending on the particular reflection (orientation of the reflectionsurface). Therefore for the circular polarization transmission, thereceiver 202 will compare the intensity variation of the received wavesignal and if there is (or approximately) constant intensity in thereceived wave the propagation, the communication between the transmitter202 and the receiver 204 may be LOS communication. To reduce thelikelihood for a LOS determination error, the technique may be combinedwith a successive receive or transmit beamforming as described below.

In step 412, the receiver 204 notifies the determination result to thetransmitter 202.

In this example, the receiver 204 characterizes the path, i.e.,determines whether the communication between the receiver 204 and thetransmitter 202 on the path is LOS, in accordance with the intensitiesof each copy of the wave signal. Procedures which will use the result(the characterization of the path), such as procedures determining adistance between the receiver 204 and the transmitter 202, can havegreater confidence in the distances determined using the ToF.

In an example embodiment, when the communication between the receiver204 and the transmitter 202 changes from LOS to NLOS (e.g., the pathcharacterization changes from LOS to NLOS), the device (which may be thereceiver 204 or the transmitter 202) may decide to initiate a handover(to start new communication) to a different device or access point(e.g., an access node), so that the device can perform LOScommunication. In other words, the device initiates a handover to adifferent device to avoid NLOS communication. For this purpose, thedevice (which may be the receiver 204 or the transmitter 202) willperiodically assess if there are neighboring devices (e.g., accessnodes) that could communicate with it in LOS to switch over to if thecurrent LOS communication fails or become NLOS. This LOS based handovercan be used, for example, to obtain a higher quality of communication(reduced pathloss), or to allow a precise tracking of the location ofthe device.

The LOS determination could also allow the remote operation of thedevice (which may be the receiver 204 or the transmitter 202), forinstance a drone, to determine a change of trajectory to maintain theLOS communication.

In an example embodiment, detection of LOS can be performedsimultaneously with multiple receivers. For instance the transmitter 202sends the same wave signal at different polarizations to multiplereceivers and then requests each receiver to report whether thecommunications between the receivers and the transmitter 202 are LOScommunication. Alternatively, the transmitter 202 sends the same wavesignal at different polarizations and then allows the LOS receiver tocompete for channel access via a random access channel procedure. Inother words, the receivers that determine that they are utilizing LOScommunications initiate random access channel procedures to content forchannel access.

In a different example embodiment, the devices record the pathcharacterization information as a function of location (e.g., thechannel at this location is NLOS or LOS) and use the stored informationfor accessing or discovery of an access node, performing an access nodediscovery, or for fast beamforming. As an example, in order to minimizethe discovery delay, the beamforming scanning could start with thedevice scanning the LOS directions (as determined from the storedinformation) and then the device performs additional search around theLOS directions if the LOS direction becomes obstructed. In other words,the device performs fast beam forming by initially scanning the LOSdirections, then if a suitable beam is not found, the device scans indirections around the LOS direction, where the LOS directions areretrieved from the stored information.

FIG. 4B illustrate example of an alternate signal flow diagram 400′ of afirst example embodiment of method for determining LOS, according to thedisclosure. The method may be performed in the context of the system asillustrated in FIG. 2A or in FIG. 2B, and may use the linear polarizedor the circular polarized as an example as illustrated in FIG. 3A or 3B.

In FIG. 4B, it is the transmitter 202 initiates the request to start LOSprocedure. That is, the transmitter 202 sends the LOS determinationrequest to the receiver 204. And the LOS determination request in step402′ comprises one or more of a number of transmissions of thetransmitter 202, and a number of polarizations of the transmitter 202.And then in step 404′, the receiver 204 sends a response to thetransmitter 202. The response in step 404′ may comprise the indicationof confirmation starting the LOS procedure. Alternatively, the responsein step 404′ may comprise one or more of a number of transmissions ofthe receiver 204, and a number of polarizations of the receiver 204.

The remaining steps of FIG. 4B (steps from 406′ to 414′) correspond tothe steps from 404 to 412 in FIG. 4A, and will not be discussed herein.

FIG. 4C illustrate example of another alternate signal flow diagram 400″of a first example embodiment of method for determining LOS, accordingto the disclosure. The method may be performed in the context of thesystem as illustrated in FIG. 2A or in FIG. 2B, and may use the linearpolarized or the circular polarized as an example as illustrated in FIG.3A or 3B.

In FIG. 4C, it is the transmitter 202 initiates the request to start LOSprocedure. That is, the transmitter 202 broadcasts the LOS determinationrequest to receivers, such as the receiver 204. The LOS determinationrequest in step 402″ comprises one or more of the number oftransmissions of the transmitter 202, and a number of polarizations ofthe transmitter 202. The transmitter 202 broadcasts, in a singletransmission or in separate transmissions, a wave signal comprising thesame bit sequence with different polarization.

The remaining steps of FIG. 4C (steps from 406″ to 412″) are the same asthe steps from 406 to 412 in FIG. 4A, and will not be discussed herein.

Prior the step 402, 402′, and 402″, the receiver 204 may send a LOSdetermining request to the transmitter 202, and the transmitter 202 andthe receiver 204 may perform a confirmation procedure to confirm boththe transmitter 202 and the receiver 204 support the procedure of LOSdetermination. The confirmation procedure may be performed by exchangingmessages between the receiver 204 and the transmitter 202, orbroadcasting messages by the transmitter 202 and the receiver 204.

The message indicating the receiver 204 or the transmitter 202 supportsthe LOS determination may be an enhanced directional multi-gigabit(EDMG) beam refinement protocol (BRP) request, and the EDMG BRP requestcomprises an element indication indicating that the device (which may bethe receiver 204 or the transmitter 202 in this example) sending theEDMG BRP request supports LOS determination.

As an example, the EDMG BRP request may follow the format shown in Table1.

TABLE 1 First example EDMG BRP request format. B0-B7 B8-B15 B16-B23B24-B31 B32-B39 B40-B50 B51-B52 B53-B56 B57-B58 Element Length ElementL- L- TX EDMG EDMG EDMG ID ID Extension RX TX-RX Sector ID TRN- Unit PTRN- Unit M TRN- Unit N Bits: 8 8 8 8 8 11 2 4 2 B59 B60 B61-B69 B70-B75B76-B83 B84 B85 B86-B87 TXSS- TXSS-REQ- TXSS- BRP CDO TX Antenna FirstPath LOS REQ RECIPROCAL SECTORS WN Mask Training Training Bits: 1 1 9 68 1 1 3

Where, the first path training element indicates that the device (whichmay be the receiver 204 or the transmitter 202 in this example) sendingEDMG BRP request supports the first path training procedure. Which meansthat the device supports the determining of which path is the shortestpath among all the path conveying the different copies of the same bitsequence, where each copy corresponds to one polarization.

The LOS training element indicates that the first device (which may bethe receiver 204 or the transmitter 202) sending the EDMG BRP requestsupports LOS determination procedure, such as those presented in FIGS.4A-4C and attendant discussion.

In another example embodiment, the first path training element may beincluded in the header of the EDMG BRP request. Alternatively, the firstpath training element may be included in a text string, which is part ofthe EDMG BRP request, for example.

As another example, the EDMG BRP request may follow the format shown inTable 2:

TABLE 2 Second example EDMG BRP request format. B1 B2-B9 B10 B11 Bl2 B13B14 Initiator L-RX TX- TX- RX- TX - TXSS- FBCK- Train- Train- TRN- FBCK-REQ Response Response OK REQ bits: 1 8 1 1 1 1 1 B15-B26 B27-B38 B39-B41B42 B43 B44-B48 B49-B50 B51-B54 TX Best Best- MID BRP- L-RX-TX TRN-U PTRN-U M sector ID Sector FBCK Extension TXSS- FB Antenna OK Id bits: 1212 3 1 1 5 2 4 B55-B56 B57 B58 B59-B67 B68-B73 B74-B81 B82 TRN-U N TXSS-TXSS-REQ- TXSS- BRP TX First REQ RECIPROCAL SECTORS CDOWN Antenna PathMask Training bits: 2 1 1 9 6 8 1 B83 B84 B88 LOS Training Reservedbits: 1 5

If the receiver 204 and transmitter 202 confirm that both thetransmitter 202 and the receiver 204 support a procedure of LOSdetermination, through the EDMG BRP request, for example, the packetcomprises an indication indicating that the copy should be used forfirst path beamforming training. Where, the First Path Training elementwhen set to a first value, e.g., ‘1’, indicates that the TRN fieldappended to this packet should be used for first path beamformingtraining. The First Path Training element when set to a second value,e.g., ‘0’, indicates that the TRN field appended to this packet shouldbe used for best performance beamforming training.

The LOS training element when set to a first value, e.g., ‘1’, indicatesthat the TRN field appended to this packet should be used for LOSbeamforming training. When the LOS training element is set to a secondvalue, e.g., ‘0’, indicates that the TRN field appended to this packetis not used for the LOS beamforming.

In the EDMG BRP request, if the first device sending the EDMG BRPrequest supports the LOS determination procedure, both the first pathtraining element and the LOS training element should be set to a firstvalue, e.g., ‘1’. Else, the first device sending the EDMG BRP requestdoes not support the LOS determination procedure.

After a second device (which may be the transmitter 202 or the receiver204 in this example) receives the EDMG BRP request, the second devicemay send a response to the first device (which sent the EDMG BRPrequest) to indicate that the second device supports the LOSdetermination procedure. The second device may also send the EDMG BRPrequest to the first device to indicate that the second device alsosupports the LOS determination procedure.

Any response from the second device or the EDMG BRP request from thesecond device may comprise an indication indicating that the device (thefirst device or the second device) supports the LOS determinationprocedure.

In other example, if the receiver 204 and transmitter 202 confirm thatboth the transmitter 202 and the receiver 204 support the Dualpolarization TRN procedure via the message, the packet comprises anindication to use the First Path beamforming training. Where, the FirstPath Training element set to a first value, e.g., ‘1’, indicates thatthe TRN field appended to this packet should be used for First Pathbeamforming training. The First Path Training element may be set to asecond value, e.g., ‘0’, to indicate that the TRN field appended to thispacket should be used for best performance beamforming training.

The LOS training element set to a first value, e.g., ‘1’, indicates thatthe TRN field appended to this packet should be used for LOS beamformingtraining. The LOS training element set to a second value, e.g., ‘0’,indicates that the TRN field appended to this packet is not used for theLOS BF.

In the EDMG BRP request, if the first device sending the EDMG BRPrequest supports the LOS determination procedure, both the first pathtraining element and the LOS training element should be set to a firstvalue, e.g., ‘1’. Else the first device sending the EDMG BRP requestdoes not support the LOS determination procedure.

After a second device (which may be the transmitter 202 or the receiver204 in this example) receiving the EDMG BRP request, the second devicemay send a response to the first device (which sent the EDMG BRPrequest) to indicate that the second device supports the LOSdetermination procedure. The second device may also send the EDMG BRPrequest to the device to indicate that the second device also supportthe LOS determination procedure.

Any of the response from the second device or the EDMG BRP request fromthe second device may comprise an indication indicating the peer deviceof the LOS determination procedure.

FIG. 5 illustrate example of a communication system 500 in the case ofwhich the propagation between transmitter 202 and receiver 204 is NLOSwith a cylindrical reflection surface 508 that obstructs LOScommunication (e.g., beam 510) with a cylindrical reflection region 509,the communication system 500 that may be used for implementing thedevices and methods disclosed herein.

That is each repetition (copy) at any polarization will suffer similarreflection, hence, at the receiver 204, the first received copies foreach transmission (e.g., beams 512, 512′, 514, 514′, 516, and 516′) willhave about the same intensity no matter the polarization at thetransmitter 202. If the transmission by the transmitter 202 and thereception by the receiver 204 is omni-directional, the receiver 204 willalways receive the same wave signal independent of the polarization atthe transmitter 202 due to the symmetry of this construction(cylindrical reflection surface 508).

However if the receiver 204 performs beamforming receiving (if thereceiver 204 receives from limited spatial directions (for instance a 3Dsolid angle)), then the ToF will be the same, but the intensity of thefirst received ray (first received copy) will change with thepolarization wave at the transmitter 202. The receiver 204 may thenconclude that the propagation is NLOS.

Therefore, as an example embodiment of the disclosure, the receiver 204may repeatedly perform beamformed receiving in different spatialdirections (and therefore potentially suffering different reflections)while the transmitter 202 will change the polarizations of transmittedwaves. If a spatial direction is found that it is invariant to thepolarization, then that spatial direction will be considered LOS. In analternative example embodiment, the transmitter 204 sends beamformedwaves in different directions, with multiple (different) polarizationsfor each direction, while the receiver 204 observes the first receivedsample intensity with respect to polarization changes, then thecommunication is considered NLOS. The addition of beamformedtransmission of different polarizations to the above described LOSprocedures may be performed, for instance, after the pathcharacterization is determined as an additional step to verify the pathcharacterization. The beamformed transmission also may be performedduring the LOS procedure itself, when polarizations and beamformed beamsare combined to determine when and if the first received copy isinvariant with respect to polarizations, which happens only in LOScommunication.

An example of achieving beamforming involves the use of a phased arrayantenna, such as a two-dimensional (2D) polarized array of antennaswhere each antenna has a phase shifter. Another example uses a polarizedhorn antenna.

FIG. 6A illustrate example of a signal flow diagram 600 of a secondexample embodiment of method for determining the LOS, according to thedisclosure. The method may be carried out in the context of the systemas illustrated in FIG. 2A or FIG. 2B, and may use the linear polarizedor the circular polarized as an example as illustrated in FIG. 3A or 3B.

In step 602, the receiver 204 requests the transmitter 202 to start theLOS determination procedure by sending a LOS determining request to thetransmitter 202. The LOS determining request may include an indicationindicating whether a dual polarization procedure for LOS is used, thedual polarization means the number of different polarizations for eachdirection is two. Same sequence is sent twice in the same direction withdifferent polarizations, for instance two orthogonal polarizations.

If the indication indicates that the dual polarization procedure for LOSis used, the transmitter 102 should send a same sequence of bits in wavesignals at two different polarizations. If the indication is that thedual polarization procedure for LOS is not used, the transmitter 202sends the bit sequence in wave signals, but not with two polarizations.FIG. 6A presents an example in which the dual polarization procedure forLOS is used.

In step 604, the transmitter 202 sends the same bit sequence in wavesignals at different polarizations. An example of such a bit sequence inIEEE 802.11ay is referred to as a training TRN sequence and is sent in adirection in space. The transmission may be in response to a prior LOSdetermining request comprising the indication indicating which dualpolarization procedure for LOS is used. Transmission at differentpolarizations may be achieved in different ways, such as with two dipoleantennas oriented orthogonally to each other, with one parallel with thesurface of the Earth and one perpendicular to the surface of the Earth.

For a single frame transmission, the data transmitted by the transmitter202 comprises multiple repetitions (copies) of the same bit sequence,with each repetition (copy) transmitted with a polarization out of thepolarizations.

Before the transmitter 202 transmits the wave signal comprising the samebit sequence to the receiver 204, the transmitter 202 may notifies theTRN power for each of the polarizations. The transmitter 202 maytransmit the same signal wave at the same power for the differentpolarizations, or the transmitter 202 may transmit the same signal waveat different powers for the different polarizations.

In step 606, the receiver 204 obtains a channel measurement for eachpolarization. Example channel measurements are presented in Table 3,which illustrates example I and Q component values with differingpolarizations for various filter taps. The channel measurements obtainedby the receiver 204, with the Channel Measurement for the First Path andDual Polarization TRN enabled, may be shown to Table 3. As shown inTable 3, for each polarization, the channel measurements comprise aRelative I Component Tap #1 Polarization #1, and a Relative Q ComponentTap #1 Polarization #1. The Relative I Component Tap #1 Polarization #1is the in-phase component of impulse response for Tap #1 (correspondingto the shortest delay), and polarization #1 in Dual Polarization TRN.The Relative Q Component Tap #1 Polarization #1 is the in-quadraturecomponent of impulse response for Tap #1 (corresponding to the shortestdelay), and polarization #1 in the Dual Polarization TRN.

If the Dual Polarization TRN procedure is not combined with the FirstPath procedure, the receiver 204 may feedback to the transmitter 202measurements for more than a single tap (first path), also illustratedin the Table 3.

In the example of Dual polarization TRN, the transmitter 202 sends thewave signal comprising the same bit sequence in two polarizations.Therefore, the receiver 204 obtains the Relative Q Component and theRelative I Component for each of the two polarizations. In otherexamples of Dual polarization TRN, the transmitter 202 sends the wavesignal comprising the same bit sequence in two different polarizationsvia the multiple path channel, the receiver 204 obtains the Relative QComponent and the Relative I Component for each path of each of the twopolarizations.

TABLE 3 Example channel for differing polarizations. Field Size MeaningDual Polarization TRN Relative I 8 bits The in-phase component ofimpulse Measurement Component Tap #1 response for Tap #1 (shortestPolarization #1 delay), and polarization # 1 in Dual Polarization TRNRelative Q 8 bits The in-quadrature component of Component Tap #1impulse response for Tap #1 Polarization #1 (shortest delay), andpolarization # 1 in Dual Polarization TRN Relative I 8 bits The in-phasecomponent of impulse Component Tap #1 response for Tap #1 (shortestPolarization #2 delay), and polarization # 2 in Dual Polarization TRNRelative Q 8 bits The in-quadrature component of Component Tap #1impulse response for Tap #1 Polarization #2 (shortest delay), andpolarization # 2 in Dual Polarization TRN Relative I 8 bits The in-phasecomponent of impulse Component Tap #2 response for Tap #2 ( ), andPolarization #1 polarization # 1 in Dual Polarization TRN Relative Q 8bits The in-quadrature component of Component Tap #2 impulse responsefor Tap #2 ( ), and Polarization #1 polarization # 1 in DualPolarization TRN Relative I 8 bits The in-phase component of impulseComponent Tap #2 response for Tap #2 ( ), and Polarization #2polarization # 2 in Dual Polarization TRN Relative Q 8 bits Thein-quadrature component of Component Tap #2 impulse response for Tap #2( ), and Polarization #2 polarization # 2 in Dual Polarization TRN . . .Relative I 8 bits The in-phase component of impulse Component Tap #Nresponse for Tap #n ( ), and Polarization #1 polarization # 1 in DualPolarization TRN Relative Q 8 bits The in-quadrature component ofComponent Tap #N impulse response for Tap #N ( ), and Polarization #1polarization # 1 in Dual Polarization TRN Relative I 8 bits The in-phasecomponent of impulse Component Tap #N response for Tap #N ( ), andPolarization #2 polarization # 2 in Dual Polarization TRN Relative Q 8bits The in-quadrature component of Component Tap #N impulse responsefor Tap #N (, and Polarization #2 polarization # N in Dual PolarizationTRN

As the example presented in Table 3, in the Dual polarization TRN, thetransmitter 202 sends wave signal comprising the same bit sequence intwo polarizations, and each polarization has N paths. The channelmeasurement for the N-th path in the two polarizations is also presentedin Table 3. The Tap #1 represents the first path the receiver measured,and Tap #N represents the N-th path the receiver measured. The firstpath has the shortest delay.

In step 608, the receiver 204 compares the channel measurements for thetwo polarizations to obtain the channel measurement difference.

In step 610, the receiver 204 determines if the channel measurementdifference between the two polarizations is larger than a threshold. Ifthe channel measurement difference between the two polarizations islarger than the threshold, the receiver 204 may determine that thetransmission between the receiver 204 and the transmitter 202 is NLOS,otherwise the transmission is LOS. The threshold may be specified in atechnical standard, or by the operator of the communications system. Thethreshold may be determined through collaboration between the devices ofthe communications system.

If the transmitter 202 sends the same bit sequence in two polarizations,and each polarization has multiple paths, the receiver 204 may comparethe channel measurement of the first path of each of the twopolarizations. If the channel measurement difference between the twopolarizations is larger than a threshold, the receiver 204 may determinethat the transmission between the receiver 204 and the transmitter 202is NLOS, otherwise the transmission may be LOS. The threshold is storedin the receiver 204. The threshold might be established beforehand orimplementation specific. The threshold needs to be sufficiently large tofilter out the possible noise and measurement errors. If the radiatedpower at the transmitter 202 for the two polarizations is different, thereceiver 204 needs to consider this difference in addition to thethreshold.

In step 612, the receiver 204 may notify the determination result to thetransmitter 102.

In this example, the receivers 204 determines if the communicationbetween the receiver 204 and the transmitter 202 is LOS based on thechannel measurements for the two polarizations to ensure thedetermination result. So that the procedures that will utilize theresult (the path characterization), such as those that determine adistance between the receiver 204 and the transmitter 202, can goodcertainty in the results.

In other example, the receiver 204 may not perform the steps 608 to 612.Instead, the receiver 204 sends the channel measurement for eachpolarization to the transmitter 202. The transmitter 202 receives thechannel measurement for each polarization and compares the channelmeasurements for the two polarizations, and characterizes the path(e.g., determines whether the channel measurement difference for the twopolarization is larger than a threshold) by performing its own versionof steps 608 and 610. If the channel measurement difference for the twopolarizations is larger than a threshold, the transmitter 202 maydetermine that the transmission between the receiver 204 and thetransmitter 202 is NLOS, otherwise the transmission is LOS.

In an example embodiment, when the communication between the receiver204 and the transmitter 202 changes from LOS to NLOS (e.g., the pathcharacterization changes from LOS to NLOS), the device (which may be thereceiver 204 or the transmitter 202 in this example) may decide tohandover (start new communication) to a different device or access point(e.g., an access node), so that the device can perform LOScommunication. In other words, the device initiates a handover to adifferent device to avoid NLOS communication. For this purpose, thedevice (which may be the receiver 204 or the transmitter 202) willperiodically asses if there are neighboring devices (e.g., access nodes)that could communicate with it in LOS to switch over to if the currentLOS communication fails or become NLOS. This LOS based handover can beused, for example, to obtain a higher quality of communication (reducedpath loss), or to allow a precise tracking of the location of thedevice.

FIG. 6B illustrate example of a signal flow diagram 600′ of a secondexample embodiment of method for determining LOS, according to thedisclosure. The method may be performed in the context of the system asillustrated in FIG. 2A or in FIG. 2B, and may use the linear polarizedor the circular polarized as an example as illustrated in FIG. 3A or 3B.

In FIG. 6B, it is the transmitter 202 initiates the request to start LOSprocedure. That is, the transmitter 202 sends a LOS determinationrequest to the receiver 204. The LOS determination request in step 602′comprises the indication indicating if a dual polarization procedure forLOS is used. And then in step 604′, the receiver 204 sends a response tothe transmitter 202. The response in step 604′ may comprise theindication indicating the initiating of the LOS procedure using the dualpolarization procedure.

The steps from 606′ to 614′ in FIG. 6B as same as the steps from 604 to612 in FIG. 6A, and will not be discussed herein.

FIG. 7 illustrates an example of a signal flow diagram 700 of a thirdexample embodiment of method for determining LOS, according to thedisclosure. The method may be performed in the context of the system asillustrated in FIG. 2A or in FIG. 2B, and may use the linear polarizedor the circular polarized as an example as illustrated in FIG. 3A or 3B.

In FIG. 7 , the transmitter 202 initiates the request to start LOSprocedure, step 702. That is, the transmitter 202 broadcasts a LOSdetermination request to the receiver 204. The LOS determination requestin step 702 comprises an indication indicating which the dualpolarization procedure for LOS is used. The transmitter 202 thenbroadcasts, during a single transmission or in separate transmissions,the same bit sequence with different polarizations, step 704.

The steps from 706 to 712 in FIG. 7 are the same as the steps from 606to 612 in FIG. 6A, and will not be discussed herein.

In other example, the receiver 204 may not perform the steps 608 to 612in FIG. 6A, the steps 610′ to 614′ in FIG. 6B, or the steps 708 to 712in FIG. 7 . Instead, the receiver 204 sends the channel measurement foreach polarization to the transmitter 202 after obtaining the channelmeasurements for each polarization. The transmitter 202 compares thechannel measurements of the two polarizations, and characterizes thepath (e.g., determines whether the channel measurement differencebetween the two polarizations is larger than a threshold) by performingits own version of the corresponding steps. If the channel measurementdifference between the two polarizations is larger than a threshold, thetransmitter 202 may determine that the transmission between the receiver204 and the transmitter 202 is NLOS, otherwise the transmission is LOS.

Prior to the step 702, the receiver 204 may send a Dual Polarizationrequest to the transmitter 202, the transmitter 202 and the receiver 204may perform a confirmation procedure to confirm both of the transmitter202 and the receiver 204 support a procedure of Dual Polarization TRNMeasurement. The confirmation procedure may be performed by exchangingmessages between the receiver 204 and the transmitter 202, orbroadcasting messages by the transmitter 202 and the receiver 204.

The LOS determination request indicating whether the dual polarizationprocedure for LOS is used may be the EDMG BRP request. The EDMG BRPrequest comprises a dual polarization TRN field. The dual polarizationTRN field indicates whether the device (which may be the receiver 204 orthe transmitter 202 in this example) is sending EDMG BRP request torequest for the Dual Polarization TRN.

As an example, the EDMG BRP request may follow the format shown in Table4.

TABLE 4 Third example EDMG BRP request format. B0 B7 B8-B15 B16-B23B24-B31 B32-B39 B40-B50 B51-B52 B53-B56 B57-B58 Element Length ElementL-RX L-TX-RX TX Sector EDMG EDMG EDMG ID ID ID TRN- TRN- TRN- ExtensionUnit P Unit M Unit N Bits: 8 8 8 8 8 11 2 4 2 B59 B60 B61 B69 B70 B75B76 B83 B85 B86 B87 . . . Digital Dual BF polarization request TRN Bits:1 1

Where, the Dual polarization TRN element (the element may also be afield) in Table 4 indicates whether the first device (which may be thereceiver 204 or the transmitter 202) that is sending EDMG BRP requestsupports the Dual polarization TRN training procedure. The Dualpolarization TRN element in Table 4 may also be an indication indicatingwhether a dual polarization procedure for LOS is used. If the DualPolarization TRN element is set to a first value, e.g., ‘1’, the DualPolarization TRN element indicates that a second device receiving theBRP is requested to send the repetitions of TRN sequences with differentpolarizations for the same antenna weight vector (AWV) beamform. Thatis, if the first device sending the EDMG BRP requests for the DualPolarization TRN, the dual polarization procedure is used. If the DualPolarization TRN element is set to a second value, e.g., ‘0’, the DualPolarization TRN element indicates that the TRN may be sent withoutpolarization change per each AWV, which means that the TRN should besent with one polarization. That is, if the device sending the EDMG BRPdoes not request for the Dual Polarization TRN, and the dualpolarization procedure is not used.

The Dual polarization TRN element indicates whether the first device(which may be the receiver 204 or the transmitter 202) sending the EDMGBRP request requests the dual polarization procedure described in FIGS.6A-B and FIG. 7 .

In another example, the Dual polarization TRN element may be included inthe header of the EDMG BRP request.

In other example, the indication that indicates whether a dualpolarization procedure is used may be included in receive vector(RXVECTOR) parameters or the receive vector (TXVECTOR) parameters. TheRXVECTOR parameters are received by the receiver 204, and the RXVECTORparameters present a physical layer (PHY) interaction during receivingof various physical layer convergence protocol (PLCP) protocol data unit(PPDU) formats. The RXVECTOR parameters are parameters for the receiver204. The TXVECTOR parameters are parameters for the transmitter 202. TheTXVECTOR parameters present a PHY interaction during transmitting of thevarious PPDU formats.

The indication that indicates whether a dual polarization procedure forLOS is used is included by the RXVECTOR parameters or the TXVECTORparameters is presented in Table 5.

TABLE 5 RXVECTOR and TXVECTOR dual polarization procedure indicator.DUAL FORMAT When set to 1, which indicates that the TRN Y YPOLARIZATION_TRNS is EMDG field appended to this packet comprising theTRN shall have different polarizations per same AWV (beamform). When setto 0, which indicates the TRN field appended to this packet comprisingthe TRN are without polarization change per each AWV (beamform)

The DUAL POLARIZATION_TRNS element in the RXVECTOR parameters or theTXVECTOR parameters, conveys whether the TRN field appended to thispacket has at least two different polarizations for each AVW. If theDUAL POLARIZATION_TRNS element in the RXVECTOR parameters or theTXVECTOR parameters is set to a first value, e.g., ‘1’, then it isindicated that the TRN field appended to the packet comprising the TRNhas different polarizations for each beamform. If the DUALPOLARIZATION_TRNS element in the RXVECTOR parameters or the TXVECTORparameters is set to a second value, e.g., ‘0’, then it is indicatedthat the TRN field appended to the packet has one polarization.

In other example, the indication that indicates whether a dualpolarization procedure for LOS is used may be included in anEMDG-Header-A field. The EMDG-Header-A field is a field structure anddefinition for a single user (SU) PPDU. The indication that indicateswhether a dual polarization procedure for LOS included in theEMDG-Header-A field may be a Dual Polarization TRN training element andan example of which is presented in Table 6 as follows.

TABLE 6 Example dual polarization procedure indicator for aEMDG-Header-A field. Dual 1 48 When set to 1, and field Number ofspatial streams (SS) equals 0 Polarization indicates that the TRN fieldsequences appended to this packet have TRN Training differentpolarization for the same sector (AWV). When set to 0 and field Numberof SS equals 0 indicates that TRN field sequences appended to thispacket are without polarization change per each AWV (beamform). Thisfield is reserved if the Number of SS field is greater than 0.

The Dual Polarization TRN Training element included in the EMDG-Header-Afield indicates whether consecutive TRN units for each AVW appended tothe packet have different polarizations. The TRN field enables thetransmitter and the receiver to perform AWV training. If the DualPolarization TRN Training element included in the EMDG-Header-A field isset to a first value, e.g., ‘1’, then it is indicated that the TRN fieldappended to the packet has different polarizations for each beamform. IfDual Polarization TRN Training element included in the EMDG-Header-Afield is set to a second value, e.g., ‘0’, then it is indicated that theTRN field appended to the packet has one polarization for each beamform.If the Dual Polarization TRN Training element included in theEMDG-Header-A field is set to a first value, e.g., ‘1’, it alsoindicated that the dual polarization procedure for LOS is used.

In other example, the indication that indicates whether a dualpolarization procedure for LOS is used may be included in anEMDG-Header-A2 subfield. The EDMG-Header-A2 subfield is transmitted inthe second low density parity check (LDPC) codeword. The indication thatindicates whether a dual polarization procedure for LOS included in theEMDG-Header-A2 subfield may be a Dual Polarization TRN training element,and an example of which is presented in Table 7 as follows:

TABLE 7 Example dual polarization procedure indicator for anEMDG-Header-A2 field. Dual Polarization 1 6 When set to 1 indicates thatthe TRN field sequences appended to this TRN Training packet havedifferent polarization for the same sector (AWV). When set to 0indicates that TRN field sequences appended to this packet are withoutpolarization change per each AWV (beamform)

The Dual Polarization TRN training element included in theEMDG-Header-A2 subfield indicates whether the TRN units appended to thispacket for each AVW have different polarizations. If the DualPolarization TRN training element included in the EMDG-Header-A2subfield is set to a first value, e.g., ‘1’, then it is indicated thatthe TRN field appended to the packet has different polarizations foreach beamform. If Dual Polarization TRN Training element included in theEMDG-Header-A2 subfield is set to a second value, e.g., ‘0’, then it isindicated that the TRN field appended to the packet has one polarizationfor each beamform. If the Dual Polarization TRN Training elementincluded in the EMDG-Header-A2 subfield is set to a first value, e.g.,‘1’, it also indicates that the dual polarization procedure for LOS isused.

In Table 7, the “1” indicates the Dual polarization TRN training elementis one bit long, and the “6” indicates the bit position of the Dualpolarization TRN training element. In Table 6, the “1” indicates theDual polarization TRN training element is one bit long, and the “48”indicates the bit position of the Dual polarization TRN trainingelement.

In other example, the indication that indicates whether a dualpolarization procedure for LOS is used may be included in a DualPolarization TRN Supported subfield of beamforming capability fieldformat. The indication that indicates whether a dual polarizationprocedure for LOS is used included the Dual Polarization TRN Supportedsubfield of beamforming capability field format may be a DualPolarization TRN Supported element, and an example of which is presentedin Table 8 as follows.

TABLE 8 Example dual polarization procedure indicator in a subfield ofbeamforming capability field format. B9 B11 B12 B13 B14B17 B18-B23 . . .First Path Hybrid Hybrid Dual Dual Reserved Training BeamformingBeamforming Polarization Polarization Supported and MU- and SU- MIMO TRNPower MIMO Supported Supported Supported Difference Bits: 11 5 1

The Dual Polarization TRN Supported element included in the subfield ofbeamforming capability field format indicates whether enable for Dualpolarization TRN procedure. If the Dual polarization TRN element is setto a first value, e.g., ‘1’, then it is indicated to enable the Dualpolarization TRN procedure, the TRN sequences may be transmitted withdifferent polarizations, which means that the Dual polarization TRNprocedure is used. If the Dual Polarization TRN Supported element is setto a second value, e.g., ‘0’, then it is indicated to not enable theDual polarization TRN procedure, the TRN sequences may be transmittedwith one polarization, which means that the Dual polarization TRNprocedure is used.

The Dual Polarization Power Difference subfield indicates a radiatedpower difference of each of the polarization. The Dual PolarizationPower Difference may be indicated as shown in Table 8.

The Dual Polarization TRN Supported element and the Dual PolarizationPower Difference may also be a dual polarization TRN capability field,and an example of which is presented in Table 9 as follows.

TABLE 9 Example dual polarization TRN capability field. DualPolarization TRN Supported TRN Power difference Bits 1 3

The indication that indicates if a dual polarization procedure for LOSis used is included in dual polarization TRN capability field format,and is shown in Table 8. The indication may also indicate whether tosupport for the Dual polarization TRN procedure. If the Dualpolarization TRN element is set to a first value, e.g., ‘1’, then it isindicated that the Dual polarization TRN procedure is supported, and theTRN sequences may be transmitted with different polarizations. If theDual polarization TRN element is set to a second value, e.g., ‘0’, thenit is indicated that the Dual polarization TRN procedure is supported,and the TRN sequences may be transmitted with one polarization.

In other example, the indication whether a dual polarization procedurefor LOS is used may be included in a DMG Beam Refinement element. TheDMG Beam Refinement element may refer to FIG. 9-512 of IEEE 802.11,which is hereby incorporated herein by reference. The Dual polarizationTRN element may replace a reserved bit in the same figure.

The dual polarization TRN element in the DMG Beam Refinement element(which is shown in FIG. 9-512) may be EDMG Dual Polarization TRN ChannelMeasurement Present. The EDMG Dual Polarization TRN Channel MeasurementPresent equal to a first value, e.g., ‘1”, indicates that the EDMGChannel Measurement Feedback element contains the Dual Polarization TRNMeasurement field. When EDMG Dual Polarization TRN Channel MeasurementPresent equal to a second value, e.g., ‘0’, indicates that the EDMGChannel Measurement Feedback element does not contain the DualPolarization TRN Measurement field.

The Dual Polarization Power Difference subfield indicates the radiatedpower difference between different polarizations. The TRN PowerDifference indicates, in dB, the difference in a radiated power for theconsecutive TRNs sequences with different polarizations.

Example radiated power differences between the first TRN subfield andthe second TRN subfield values are shown in Table 10.

TABLE 10 Example first TRN subfield and second TRN subfield valuedifferences. TRN power difference between the first TRN polarization andthe second TRN TRN Power difference bits polarization(dB) 000   0 001  1 010   2 011 3 or larger 101 −1 110 −2 111 −3 100 −4 or smaller

The polarization described in relation with the discussion of FIGS. 6A,6B, and 7 , and Tables 3-10 specifies details for the dual polarizationprocedure. Dual polarization comprises two polarizations, for example.In the dual polarization procedure for LOS determination, the same TRN(the same bit sequence in wave signals) is sent in the same directionswith the two different polarizations, one of the two polarizations maybe referred to the first polarization, the other of the twopolarizations may be referred to the second polarization. Therefore, thefirst TRN is the first polarization transmitted TRN in the direction,the second TRN is the second polarization transmitted TRN in the samedirection.

The polarization described from FIGS. 2A to 4C, and FIG. 5 , and Tables1 and 2 is different polarizations for different directions, such as avertical polarization, a horizontal polarization and a 45 degreespolarization. Different direction polarizations correspond to differentpaths.

In other example, the procedure of LOS determination described in FIGS.2A to 3C, FIG. 5 , and Tables 1 and 2 may be combined with the procedureof LOS determination described in FIGS. 6A, 6B, and 7 , and Tables 3-10.The LOS determining request described in steps 402, 402′, 402″, 602,602′, and 702, may comprise the indication indicating if a dualpolarization procedure is used, and may be combined with first pathtraining.

If the receiver 204 and transmitter 202 confirm both of the transmitter202 and the receiver 204 support the Dual polarization TRN procedure andthe indication of first path training via the message, the packetcomprises an indication that indicates the use of the First Pathbeamforming training and the indication that indicates the use of a dualpolarization procedure is used.

When the LOS procedure utilizes only two different polarizationstransmissions of the same TRN sequence, the procedure is referred to asDual Polarization TRN.

As previously stated a Dual Polarization TRN procedure involvestransmitting twice the same TRN sequence at different polarization andthe receiver measuring the received signal at each polarization.

The Dual Polarization TRN procedure (for LOS) can be combined with theFirst Path Training or not.

If the Dual Polarization TRN procedure is combined with the First PathTraining the receiver will measure only the first received copy (tap)for each polarizations transmission. In order to do this thetransmission of the EDMG BRP Request should have enabled both First PathBF and Dual Polarization TRN procedures.

Embodiment solutions may be used in Third Generation Partnership Project(3GPP) New Radio (NR) applications, where obtaining accurate locationinformation may be an important consideration. The potential commercialapplications of accurate location may, for example, apply to indoorpositioning using millimeter wavelength (mmW) access points. Havinginformation about the characterization of the path (or LOS or NLOSpropagation) can be used to improve accuracy of location methods. Forinstance, a UE may identify whether or which received beam (or ray) isLOS, and performs positioning using LOS beams (or rays) only. In someexample embodiments, the previously described technique of LOSdetermination may be applied using polarization for NR. While thedescription is made for mmW propagation (frequency range two (FR2)), itis also applicable to microwave propagation (frequency range one (FR1)).

The 3GPP standardized multiple positioning techniques for Long TermEvolution (LTE). In addition, some new techniques are considered for NR.3GPP LTE Contribution R1-1809348, which is incorporated herein in itsentirety by reference, provides a summary of example positioningtechniques. A summary of portions of R1-1809348 is provided below.

In NR, the Enhanced cell identifier (ECID) is to estimate UE locationbased on the detected cell-ID in combination with assisted measurementswhich could be the Tx-Rx time difference in type 1 and 2, angle ofarrival (AOA) of serving cell, reference signal received power (RSRP),reference signal received quality (RSRQ), and related qualitymeasurements (similar to LTE). The reference signals in NR used in themeasurements could be the primary synchronization signal (PSS), thesecondary synchronization signal (SSS), the physical random accesschannel (PRACH), and the sounding reference signal (SRS). Because theLTE common reference signal (CRS) is not supported in NR, NR could usecell-specific reference signals in the downlink for measurements, suchas the downlink tracking reference signal (TRS) or the channel stateinformation reference signal (CSI-RS). In NR, the ECID-based positioningcould be performed at the UE side with assistance of network data, or atthe network side with both UE measurements and gNB measurements.

In NR, the observed time difference of arrival (OTDOA) technique is adownlink positioning method where the UE measures the reference signaltime difference (RSTD) of arrival between a reference gNB andneighboring gNBs. The reference signal for positioning in downlink maybe flexible, scalable in bandwidth, and available to all UEs. Acell-specific positioning reference signal (PRS), similar to the LTEPRS, is recommended to be defined in the NR downlink to reach theobjectives. Related studies include, but not limit to, the design of PRSpattern, sequence design, power boosting, configurable ID, intra orinter-frequency RSTD measurements, support of multi-Transmit-ReceivePoint (TRP) or cell PRS transmission, and combination with beammanagement mechanisms to support both FR1 and FR2, and signalprocedures. An alternative method, if PRS is not allowed, is to possiblyreuse existing NR reference signals (e.g., TRS) with minor changes sothat they can perform the same functions as PRS.

In NR, the uplink time difference of arrival (UTDOA) technique is anetwork-based positioning method that uses the uplink SRS to estimatethe RSTD between a reference gNB and neighboring gNBs. The NR UTDOA is amandatory function because it is well suited to exploit the network dataand measurements to estimate high-accuracy location while saving the PRSoverhead because multiple gNBs could receive the uplink SRSsimultaneously. NR supports beam management and multiple TRPs for bothFR1 and FR2, thus NR UTDOA may consider the combination with beammanagement and multiple TRPs techniques to obtain high-quality UTDOAmeasurements.

Uplink AOA (UAOA)-based positioning may be used to estimate UE locationby measuring the AOAs of the uplink reference signals. The uplink SRSmay be used for measuring AOAs in gNBs or TRPs but other referencesignals (e.g., the demodulation reference signal (DMRS)) are notexcluded. UAOAs may be measured for both elevation and zenith angles inorder to attain the 3D location.

The UAOA positioning is triggered by the Location Management Function(LMF) of the NR positioning architecture. The LMF coordinates with theserving cell and related neighboring cells to provide UAOA measurementsfor location estimation. Related measurements such as number of antennasmay be also provided to assess the quality of UAOA measurements and toassist the LMF to perform localization.

Because both UTDOA and UAOA utilize uplink SRS for measurements andpositioning, the UAOA-based positioning can apply the similar signalingprocedure as performed in UTDOA, but additional design may be consideredwhen both UE and gNBs or TRPs use transmit beamforming (e.g., for FR2operation).

Downlink angle of departure (DAOD)-based positioning may be used in somesituations. Similar to UAOA, it is feasible to estimate UE location interms of DAODs of multiple gNBs or TRPs. The DAODs are the AODs of thestrongest path from the gNBs, and can be measured by the UE. Forexample, the UE can measure the channel on all available beams receivedfrom the gNBs and feedback this information to the network so that thenetwork can determine the AODs of the strongest path. Compared withUAOA, DAOD needs UE assistance for measurement feedback. The downlinkreference signals used by UE could be downlink PSS, SSS, CSI-RS, etc.

While the DAOD procedure is different from UAOA, there are a lot ofcommonalities and a consistent uniform framework for ABP can bestandardized.

These techniques can be classified into one of two types of solutions,namely UE-centric solutions and eNB-centric solutions. In UE-centricsolutions (e.g., TDOA), the eNB transmits some signals (e.g., referencesignals, such as the PRS) that the UE uses to perform measurements. TheUE then reports these measurements. In eNB-centric solutions (e.g.,UTDOA), the eNB performs measurements of signals or messages sent by theUE. In NR, the solutions may be classified into one of two types,UE-centric or gNB-centric (which is similar to eNB-centric in LTE)solutions.

Example embodiments provide LOS determination using UE-centricsolutions. For OTDOA in LTE, the eNB sends a reference signal (e.g., thePRS) that the UE uses to determine the time of arrival. Measurements areperformed for multiple eNBs, and time differences between eNBs arereported to the serving eNB. The PRS configuration is performed usingRRC signaling. The RSTD measurements made by the UE are also sent by RRCsignaling. It is reasonable to assume a similar approach for NR,although the signaling details could be different (e.g., sent in aphysical layer message such as downlink control information (DCI),uplink control information (UCI), through MAC messages, etc.).

FIG. 8A illustrates a flowchart 800 of an example method for UEoperations in a UE-centric solution. The UE sends an indication that ithas the capability to perform LOS measurements with signals havingdifferent polarizations (block 805). The capability to perform LOSmeasurements may mean that the UE can perform measurements, for example.An OTDOA capability may be defined as follows:

OTDOA-PositioningCapabilities-r10 : := SEQUENCE {    otdoa-UE-assisted-r10 ENUMERATED { supported} ,    interFreqRSTDmeasurement-r10 ENUMERATED { supported} OPTIONAL }

An OTDOA-PositioningCapabilities capability may be defined, and aLOS-ue-assisted field could be added to indicate whether the UE supportsLOS determination or not.

The UE receives a RS, e.g., the PRS, configuration (block 807). In LTE,the PRS configuration is received through a higher-layer message. TheRRC signaling indicates a measurement gap where the UE can expect thePRS. This procedure can be extended in several ways. In one example, themeasurement gap is extended so that the UE can perform two measurementsduring the gap (one for a first polarization (e.g., the horizontalpolarization), and one for a second polarization (e.g., the verticalpolarization)). The length of the measurement gap depends on a number offactors including the numerologies of the RS for positioning, thetransmission duration (in terms of number of orthogonal frequencydivision multiplexed (OFDM) symbols), extra time needed for propagationdelay uncertainty, and etc. In this case, the two PRS is multiplexed ina TDM manner onto the time and frequency resources at the transmitter.

The length, duration, or interval of the measurement gap is for a singlemeasurement, but the UE is expected to perform the two measurementssimultaneously. For such a situation, two different PRS sequences needto be sent at the same time: PRS_hor for horizontal polarization, andPRS_ver for the vertical polarization. These two PRS sequences (orresources) may be multiplexed at the transmitter in a frequency divisionmultiplexed (FDM) or code division multiplexed (CDM) manner onto thetime and frequency resources defined as resource elements for NR.

There are two separate gaps configured: one for PRS_hor, one forPRS_ver. However, this solution may only work for nomadic or stationaryscenarios, because in order to determine if a ray is LOS, the UE maygenerally receive signal with substantially the same channel when thegNB transmits with horizontal or vertical polarizations.

The UE performs measurements (block 809). In order to performmeasurements, the UE may generally receive a known RS. A RS is generallydefined by a bit sequence and its mapped time and frequency resourceswhich is a set of resource elements. For LTE, a unique positioningreference signal is defined, the PRS. The PRSs can be also used toestimate the channel, such as the CIR, at the receiver.

Because the UE has to perform measurements for both polarizations, theUE needs to be able to know with which polarization angle the gNBtransmitted the signal. There are several ways to do this:

-   -   Two different PRS sequences may be defined: PRS_hor and PRS_ver.        If the two sequences are orthogonal, the UE can even        simultaneously and independently measure the signals for both        polarizations. One simple way to achieve that is to scramble a        given PRS sequence with different orthogonal codes for the        horizontal polarization and vertical polarization transmissions.    -   The same sequence may be sent at two different time instances,        which are known by the UE. The time instances may generally be        close enough so that the channel does not substantially change.

In one example embodiment, a set of two reference signal resources canbe defined with one resource defined for PRS_hor and another resourcedefined for PRS_ver. In another example embodiment, a reference signalof two antenna ports can be defined with one antenna port defined forhorizontal polarization measurement and another defined for verticalpolarization measurement. The embodiment here refers to two orthogonalpolarization, however it can be straightforward extended to multipledistinct polarizations. For N distinct polarization, as set of Northogonal sequences PRS_1, . . . , PRS_N can be used, where thesequence PRS_n is associate to the nth transmit polarization.

The reflectance (i.e., the intensity reflection coefficient) is thesquare of the amplitude reflection coefficient. From the Fresnelequations and the Snell's law, it is possible to derive the reflectancecoefficients for the parallel and orthogonal polarizations as follows:

$R_{} = \frac{{\tan}^{2}\left( {\theta_{i} - \theta_{t}} \right)}{{\tan}^{2}\left( {\theta_{i} + \theta_{t}} \right)}$$R_{\bot} = \frac{{\sin}^{2}\left( {\theta_{i} - \theta_{t}} \right)}{{\sin}^{2}\left( {\theta_{i} + \theta_{t}} \right)}$

Where the angle of the incidence at the reflection surface between afirst medium and a second medium is θ_(i), and θ_(t) is the angle oftransmission into the second medium. For the electromagnetic wavetravelling from a medium of lower to higher index of refraction thedifference θ_(i)−θ_(t) is positive. The main observation for the purposeof this disclosure is that the reflected coefficients for the paralleland orthogonal polarizations are different.

A UE measurement needs to be defined for LOS detection. The Table 11presents the UE measured reference signal time difference (RSTD) forOTDOA.

TABLE 11 UE measured RSTD for OTDOA. Definition The relative timingdifference between the neighbor cell j and the reference cell i, definedas S_(ubframe) − T_(SubframeRxi), where: T_(SubframeRxj) is the timewhen the UE receives the start of one subframe from cell jT_(SubframeRxi) is the time when the UE receives the corresponding startof one subframe from cell i that is closest in time to the subframereceived from cell j. The reference point for the observed subframe timedifference shall be the antenna connector of the UE. Applicable forRRC_CONNECTED intra-frequency RRC_CONNECTED inter-frequency RRC_IDLEintra-frequency only applicable for NB-IoT UEs RRC_IDLE inter-frequencyonly applicable for NB-IoT UEs

For LOS detection, different measurements may be defined. In one exampleembodiment, the measurement is a difference or ratio of the RSRPmeasured on the two PRSs resources or antenna ports at the same receivetime. As the UE usually experiences multipath propagation environments,RSRPs and their ratio need to be measured for a same path of themultiple paths. In the case of cross-polarized antennas at the UEreceiver, the measured RSRPs of each PRS for this path on the antennasof both polarizations need to be summed together. The measurements at UEare performed for the first received path, because the first receivedpath is the candidate for the LOS propagation. How to distinguishbetween the first received path and the next received path is a matterof implementation where the noise and resolution could impact theidentity of the first received path. The UE may report the measured RSRPfor each PRS, the difference or ratio of the RSRPs between the two PRSs,or an indication of the path characterization (e.g., LOS or NLOS) wherethe indication can be binary (i.e., LOS or NLOS) or multiple levels toshow the likelihood or confidence of its estimation of LOS or NLOS. Inanother example embodiment, the UE only report the TOA (or RSTD) forTRPs or cells that it deems to have LOS communication between the UE andthe TRP or cell.

It may be useful to first define a UE measurement of received power of aRS on a single path of the multiple channel, which is shown in Table 12.This is a different measurement from what is defined in the current 3GPPspecification of RSRP where received power of all paths are consideredtogether as shown in the following definition from 3GPP TS 38.215V15.2.0, which is herein incorporated by reference in its entirety. Insome examples, the capability of the UE to measure the first path may becommunicated to the eNB. If the UE cannot measure the first path, butcould measure just the aggregate of all paths, the LOS procedure couldstill take place, however the LOS determination may be successful onlyin the particular situation when there are no reflections, i.e., onlydirect propagation, which is a less likely situation. The eNB may beaware of the UE limitation via a previous capability exchange.

TABLE 12 UE measurement of RS received power Definition CSI referencesignal received power (CSI-RSRP), is defined as the linear average overthe power contributions (in [W]) of the resource elements that carry CSIreference signals configured for RSRP measurements within the consideredmeasurement frequency bandwidth in the configured CSI-RS occasions. ForCSI-RSRP determination CSI reference signals transmitted on antenna port3000 according to 3GPP TS 38.211 [4] shall be used. If CSI-RSRP is usedfor L1-RSRP, CSI reference signals transmitted on antenna ports 3000,3001 can be used for CSI-RSRP determination. For intra-frequencyCSI-RSRP measurements, if the measurement gap is not configured, UE isnot expected to measure the CSI-RS resource(s) outside of the activedownlink bandwidth part. For frequency range 1, the reference point forthe CSI-RSRP shall be the antenna connector of the UE. For frequencyrange 2, CSI-RSRP shall be measured based on the combined signal fromantenna elements corresponding to a given receiver branch. For frequencyrange 1 and 2, if receiver diversity is in use by the UE, the reportedCSI-RSRP value shall not be lower than the corresponding CSI-RSRP of anyof the individual receiver branches. Applicable for If CSI-RSRP is usedfor L1-RSRP, RRC_CONNECTED intra-frequency. Otherwise, RRC_CONNECTEDintra-frequency, RRC_CONNECTED inter-frequency

The number of resource elements within the considered measurementfrequency bandwidth and within the measurement period that are used bythe UE to determine CSI-RS RSRP is an implementation issue with thelimitation that corresponding measurement accuracy requirements have tobe fulfilled. The power per resource element is determined from theenergy received during the useful part of the symbol, excluding thecyclic prefix (CP).

A new measurement of received power of a reference signal on a singlepath of the multiple channel can be defined as shown in Table 13.

TABLE 13 RSRP measurement on a single path of a multichannel scenario.Definition Reference signal received power over a path (RSRP-p), isdefined as the linear average over the power contributions (in [W]) ofthe resource elements that carry a reference signals (e.g., apositioning reference signal or a CSI-RS or a set of CSI-RS resources)configured for RSRP-p measurements within the considered measurementfrequency bandwidth over a single (first and/or strongest) path in theconfigured RS occasions. For frequency range 1, the reference point forthe RSRP-p shall be the antenna connector of the UE. For frequency range2, RSRP-p shall be measured based on the combined signal from antennaelements corresponding to a given receiver branch. For frequency range 1and 2, if multiple polarized antennas or receiver branches are in use bythe UE, the reported RSRP-p value shall be the sum of the RSRP-p of anyof the individual receiver branches.

The number of resource elements within the considered measurementfrequency bandwidth and within the measurement period that are used bythe UE to determine RSRP-p may be left up to the UE implementation withthe limitation that corresponding measurement accuracy requirements haveto be fulfilled. The power per resource element may be determined fromthe energy received during the useful part of the symbol, e.g.,excluding the CP.

The UE reports the polarization measurements (block 811). UEs may reportpolarization measurements to the gNB in a higher layer message. The UEmay either report two RSRP values (or signal plus interference to noiseratio (SINR), RSRP, received signal strength indicator (RSSI), etc.) tothe gNB: a first value for the horizontal polarization, and a secondvalue for the vertical polarization. Alternatively, the UE may report aratio of these two RSRP values. The UE may also determine on its own thecharacterization of the path (e.g., using a pre-configured threshold andhaving the UE comparing an SINR ratio to this threshold) and report itto the gNB.

In an embodiment, the polarization measurements may be included in thesame message as the one used to report the RSTD measurements.

In some example embodiments, measurements are performed over the firstpath however in a different example embodiment the measurement may beperformed for the strongest path or a combination of the first andstrongest paths.

FIG. 8B illustrates a flowchart 850 of an example method for gNBoperations in a UE-centric solution. The gNB receives an indication thatthe UE has the capability to perform LOS measurements with signalshaving different polarizations (block 855). The gNB sends a RS, e.g.,the PRS, configuration (block 857). The RS configuration may be sentusing higher layer signaling. The gNB receives polarization measurements(block 859). The polarization measurements may be received in a higherlayer message. The report may include two RSRP values (or SINR, RSRP,RSSI, etc.): a first value for the horizontal polarization, and a secondvalue for the vertical polarization. Alternatively, the report mayinclude a ratio of these two RSRP values. The UE may also determine onits own the characterization of the path (e.g., using a pre-configuredthreshold and having the UE comparing an SINR ratio to this threshold)and the report may include the characterization of the path.

Example embodiments provide LOS determination techniques for gNB-centricsolutions. For gNB-centric solutions, the UE transmits with twopolarizations, and the gNB performs the measurement of the transmission,in a manner similar to the measurements made by the UE in the UE-centricsolutions. The capability to perform LOS measurements may mean thateither the gNB or the UE can perform measurements, for example.

FIG. 9A illustrates a flowchart 900 of an example method for UEoperation in a gNB-centric solution. This operation is similar to theone for the UE-centric procedure, except that the UE indicates itscapability to transmit with two polarizations instead of receiving withtwo polarizations. The UE sends an indication that it has the capabilityto transmit signals having different polarizations (block 905). Theindication may be sent using higher layer signaling, such as in DCI. TheUE receives a request to transmit with multiple polarizations (block907). The request may be received over higher layer signaling. Therequest may also configure a RS (such as a SRS), polarizations totransmit, resource elements or antenna ports to use, multiplexing (TDM,CDM, FDM, or a combination thereof) to use, and so on. The UE transmitsthe RS with multiple polarizations (block 909).

With respect to higher layer messaging of the RS configuration, atechnique similar to the description of the OTDOA technique may be used.The RS configuration may specify that the UE send an SRS. Just like thePRS, in order to differentiate between the two polarities, two SRSsequences may be needed, and may be obtained by scrambling the SRS witha different sequence for each of the horizontal and verticalpolarizations. Different time instances may be used, but theinterference experienced at two different time instances may bedifferent. An additional bit may be included in the DCI to indicate thatthe SRS needs to be transmitted with both polarizations.

FIG. 9B illustrates a flowchart 950 of an example method for gNBoperation in a gNB-centric solution. The gNB receives an indication thata UE has the capability to transmit signals having differentpolarizations (block 955). The indication may be sent using higher layersignaling. The gNB sends a request for the UE to transmit a RS withmultiple polarizations (block 957). The request may be sent over higherlayer signaling. The request may also configure a RS, polarizations totransmit, resource elements or antenna ports to use, multiplexing (TDM,CDM, FDM, or a combination thereof) to use, and so on. The gNB receivesthe RS with the multiple polarizations (block 959). The RS is receivedin accordance with the configuration of the RS. In addition to receivingthe RS, the gNB makes polarization measurements, which are also made inaccordance with the configuration of the RS. The gNB also characterizesthe paths in accordance with the polarization measurements. As anexample, the gNB compares the polarization measurements with apre-specified threshold and if the polarization measurements meet thethreshold, the UE and gNB are performing LOS communication, else theyare performing NLOS communication.

In one example embodiment, a method for signaling to support LOSdetection is provided. The signaling may be communicated prior to theassociation of UE with the access node. Alternatively, the signaling maybe communicated after or during the association of UE with the accessnode. For WLAN technology such as IEEE 802.11 compliant devices, aninformation element (IE) can have a field, for instance, a bit, thatsignals the support of the LOS detection feature. The IE could beprovided in Probe Request frames, Probe Response frames, (Re)Association Request frames, (Re) Association Response frames, Beaconsframes, or other type of management or action frames.

In another example embodiment, a method for transmitting multipletransmissions with different polarizations is provided. The transmissionmay be simultaneous or sequential, and may use the same power for eachpolarization or a set of known and pre-established powers for eachpolarization.

In another example embodiment, a method for receiving multipletransmissions with different polarizations is provided. In one example,the receiver is able to receive in each of the transmitted polarizationplanes and discriminate between copies of the transmitted signals (beamsor rays), and where the receiver compares the received power of thefirst received ray for each corresponding transmitted polarization.

Other example embodiments include: (1) a method where the receiverdecides that if the received powers for the first received ray forvarious polarizations are the same, the transmitter and the receiver areLOS, otherwise the transmitter and the receiver are NLOS; (2) a methodwhere the receiver uses the first ray received in LOS communication todetermine the distance between transmitter and the receiver using theToF of the communication; (3) a method where the receiver determines ifthe first received ray is LOS or NLOS and communicates thecharacterization back to the transmitter; (4) a method where thetransmitter is informed if the communication is LOS or NLOS and use theToF to determine the distance between the transmitter and the receiver;(5) a method where a receiver determines if the first receive ray (copyof the signal) is LOS and use the information of the direction ofarrival (DOA) of the first ray to determine the angle of the transmitterlocation; (6) a method to determine the change of LOS communication,where receiver initiates a handover to a new LOS communication with adifferent transmitter if the current LOS communication becomes NLOS; (7)a method to determine the change from LOS to NLOS communication and toreport the change to the second device, for instance, a base station orAP, where the second device sends a control (e.g., link management)message to trigger the handover to a new LOS communication link with adifferent device (e.g., an AP); (8) a method to periodically assess theLOS or NLOS status of a communication with multiple devices and todecide to switch the communication to a LOS device; (9) a method for adevice to periodically assess the LOS or NLOS status of a communicationwith a second device for the purpose of remote control of the seconddevice and modify the trajectory of the second device to maintain theLOS or NLOS communication status; (10) a method to assess the LOSstatus, to record the LOS status with respect to location and differentcommunications nodes (base stations, access points, relays, accessnodes, etc.) and use it later for fast discovery and fast attachmentsuch as antenna beamforming on the direction of LOS, or recovery whenthe LOS communication gets obstructed to alternate LOS directions ofcommunications; (11) a method where the device is communicating usingbeamforming towards a known LOS communication direction for fastdiscovery, and if the discovery fails it searches in adjacent directionsof LOS. Other examples are also possible.

FIG. 10 illustrates a flow diagram of example operations 1000 occurringin a UE in a UE-centric LOS measurements solution. Operations 1000 maybe indicative of operations occurring in a UE as the UE participates ina UE-centric LOS measurements solution.

Operations 1000 begin with the UE communicating a LOS determinationrequest (block 1005). The UE may send the LOS determination request tothe gNB or receive the LOS determination request from the gNB. The LOSdetermination request, when received from the gNB, may include a RSconfiguration. The UE measures the first signal on the channel (block1007). The first signal may be a bit sequence with a first polarization.Copies of the first signal may be received on one or more paths. The UEmeasures the second signal on the channel (block 1009). The secondsignal may be a bit sequence with a second polarization. Copies of thesecond signal may be received on one or more paths. The UE may transmitthe channel measurements to the access node (block 1011). In someembodiments, the UE provides the channel measurements to the gNB, whichperforms the characterization of the paths itself.

The UE may perform a comparison of a difference of the channelmeasurements with a pre-specified threshold (block 1013). In someembodiments, the UE characterizes the paths and provides thecharacterization of the paths to the gNB. If the difference of thechannel measurements is less than the threshold, then the path is LOS(block 1015) and the UE transmits the characterization to the gNB (block1017). If the difference of the channel measurements is greater than thethreshold, then the path is NLOS (block 1019) and the UE transmits thecharacterization to the gNB (block 1017). If the UE did not send channelmeasurements, the UE may send the characterization of the paths to thegNB (block 1117). Although the discussion focusses on the UE interactingwith the gNB, the example embodiments are also operable with other formsof communications controllers, such as APs, access nodes, base stations,etc.

FIG. 11 illustrates a flow diagram of example operations 1100 occurringin a gNB in a UE-centric LOS measurements solution. Operations 1100 maybe indicative of operations occurring in a gNB as the gNB participatesin a UE-centric LOS measurements solution.

Operations 1100 begin with the gNB communicating a LOS determinationrequest (block 1105). The gNB may send the LOS determination request tothe UE or receive the LOS determination request from the UE. The gNBtransmits the first signal on the channel (block 1107). The first signalmay be a bit sequence with a first polarization. The gNB transmits thesecond signal on the channel (block 1109). The second signal may be abit sequence with a second polarization. The gNB may receive the channelmeasurements from the UE (block 1111). In some embodiments, the UEprovides the channel measurements to the gNB, which performs thecharacterization of the paths itself.

The gNB may perform a comparison of a difference of the channelmeasurements with a pre-specified threshold (block 1113). In someembodiments, the gNB characterizes the paths and optionally provides thecharacterization of the paths to the UE. If the difference of thechannel measurements is less than the threshold, then the path is LOS(block 1115) and the gNB optionally transmits the characterization tothe UE (block 1117). If the difference of the channel measurements isgreater than the threshold, then the path is NLOS (block 1119) and thegNB optionally transmits the characterization to the UE (block 1117). Ifthe gNB did not receive channel measurements, the gNB may receive thecharacterization of the paths from the UE (block 1117). Although thediscussion focusses on the UE interacting with the gNB, the exampleembodiments are also operable with other forms of communicationscontrollers, such as APs, access nodes, base stations, etc.

FIGS. 10 and 11 presented flow diagrams of example operations occurringin a UE and a gNB in a UE-centric LOS measurements solution. Flowdiagrams of example operations occurring in a UE and a gNB in agNB-centric LOS measurements solution would be similar with theexception that the UE would be sending the bit sequences with differentpolarities and the gNB would be making the channel measurements.Furthermore, in the gNB-centric LOS measurements solution, it would beunlikely for the gNB to send the channel measurements to the UE for theUE to perform the characterization of the paths.

FIG. 12 illustrates an example communication system 1200. In general,the system 1200 enables multiple wireless or wired users to transmit andreceive data and other content. The system 1200 may implement one ormore channel access methods, such as code division multiple access(CDMA), time division multiple access (TDMA), frequency divisionmultiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA(SC-FDMA), or non-orthogonal multiple access (NOMA).

In this example, the communication system 1200 includes electronicdevices (ED) 1210 a-1210 c, radio access networks (RANs) 1220 a-1220 b,a core network 1230, a public switched telephone network (PSTN) 1240,the Internet 1250, and other networks 1260. While certain numbers ofthese components or elements are shown in FIG. 12 , any number of thesecomponents or elements may be included in the system 1200.

The EDs 1210 a-1210 c are configured to operate or communicate in thesystem 1200. For example, the EDs 1210 a-1210 c are configured totransmit or receive via wireless or wired communication channels. EachED 1210 a-1210 c represents any suitable end user device and may includesuch devices (or may be referred to) as a user equipment or device (UE),wireless transmit or receive unit (WTRU), mobile station, fixed ormobile subscriber unit, cellular telephone, personal digital assistant(PDA), smartphone, laptop, computer, touchpad, wireless sensor, orconsumer electronics device.

The RANs 1220 a-1220 b here include base stations 1270 a-1270 b,respectively. Each base station 1270 a-1270 b is configured towirelessly interface with one or more of the EDs 1210 a-1210 c to enableaccess to the core network 1230, the PSTN 1240, the Internet 1250, orthe other networks 1260. For example, the base stations 1270 a-1270 bmay include (or be) one or more of several well-known devices, such as abase transceiver station (BTS), a Node-B (Node), an evolved NodeB(eNodeB), a Next Generation (NG) NodeB (gNB), a Home NodeB, a HomeeNodeB, a site controller, an access point (AP), or a wireless router.The EDs 1210 a-1210 c are configured to interface and communicate withthe Internet 1250 and may access the core network 1230, the PSTN 1240,or the other networks 1260.

In the embodiment shown in FIG. 12 , the base station 1270 a forms partof the RAN 1220 a, which may include other base stations, elements, ordevices. Also, the base station 1270 b forms part of the RAN 1220 b,which may include other base stations, elements, or devices. Each basestation 1270 a-1270 b operates to transmit or receive wireless signalswithin a particular geographic region or area, sometimes referred to asa “cell.” In some embodiments, multiple-input multiple-output (MIMO)technology may be employed having multiple transceivers for each cell.

The base stations 1270 a-1270 b communicate with one or more of the EDs1210 a-1210 c over one or more air interfaces 1290 using wirelesscommunication links. The air interfaces 1290 may utilize any suitableradio access technology.

It is contemplated that the system 1200 may use multiple channel accessfunctionality, including such schemes as described above. In particularembodiments, the base stations and EDs implement 5G New Radio (NR), LTE,LTE-A, or LTE-B. Of course, other multiple access schemes and wirelessprotocols may be utilized.

The RANs 1220 a-1220 b are in communication with the core network 1230to provide the EDs 1210 a-1210 c with voice, data, application, Voiceover Internet Protocol (VoIP), or other services. Understandably, theRANs 1220 a-1220 b or the core network 1230 may be in direct or indirectcommunication with one or more other RANs (not shown). The core network1230 may also serve as a gateway access for other networks (such as thePSTN 1240, the Internet 1250, and the other networks 1260). In addition,some or all of the EDs 1210 a-1210 c may include functionality forcommunicating with different wireless networks over different wirelesslinks using different wireless technologies or protocols. Instead ofwireless communication (or in addition thereto), the EDs may communicatevia wired communication channels to a service provider or switch (notshown), and to the Internet 1250.

Although FIG. 12 illustrates one example of a communication system,various changes may be made to FIG. 12 . For example, the communicationsystem 1200 could include any number of EDs, base stations, networks, orother components in any suitable configuration.

FIGS. 13A and 13B illustrate example devices that may implement themethods and teachings according to this disclosure. In particular, FIG.13A illustrates an example ED 1310, and FIG. 13B illustrates an examplebase station 1370. These components could be used in the system 1200 orin any other suitable system.

As shown in FIG. 13A, the ED 1310 includes at least one processing unit1300. The processing unit 1300 implements various processing operationsof the ED 1310. For example, the processing unit 1300 could performsignal coding, data processing, power control, input/output processing,or any other functionality enabling the ED 1310 to operate in the system1200. The processing unit 1300 also supports the methods and teachingsdescribed in more detail above. Each processing unit 1300 includes anysuitable processing or computing device configured to perform one ormore operations. Each processing unit 1300 could, for example, include amicroprocessor, microcontroller, digital signal processor, fieldprogrammable gate array, or application specific integrated circuit.

The ED 1310 also includes at least one transceiver 1302. The transceiver1302 is configured to modulate data or other content for transmission byat least one antenna or NIC (Network Interface Controller) 1304. Thetransceiver 1302 is also configured to demodulate data or other contentreceived by the at least one antenna 1304. Each transceiver 1302includes any suitable structure for generating signals for wireless orwired transmission or processing signals received wirelessly or by wire.Each antenna 1304 includes any suitable structure for transmitting orreceiving wireless or wired signals. One or multiple transceivers 1302could be used in the ED 1310, and one or multiple antennas 1304 could beused in the ED 1310. Although shown as a single functional unit, atransceiver 1302 could also be implemented using at least onetransmitter and at least one separate receiver.

The ED 1310 further includes one or more input/output devices 1306 orinterfaces (such as a wired interface to the Internet 1250). Theinput/output devices 1306 facilitate interaction with a user or otherdevices (network communications) in the network. Each input/outputdevice 1306 includes any suitable structure for providing information toor receiving information from a user, such as a speaker, microphone,keypad, keyboard, display, or touch screen, including network interfacecommunications.

In addition, the ED 1310 includes at least one memory 1308. The memory1308 stores instructions and data used, generated, or collected by theED 1310. For example, the memory 1308 could store software or firmwareinstructions executed by the processing unit(s) 1300 and data used toreduce or eliminate interference in incoming signals. Each memory 1308includes any suitable volatile or non-volatile storage and retrievaldevice(s). Any suitable type of memory may be used, such as randomaccess memory (RAM), read only memory (ROM), hard disk, optical disc,subscriber identity module (SIM) card, memory stick, secure digital (SD)memory card, and the like.

As shown in FIG. 13B, the base station 1370 includes at least oneprocessing unit 1350, at least one transceiver 1352, which includesfunctionality for a transmitter and a receiver, one or more antennas1356, at least one memory 1358, and one or more input/output devices orinterfaces 1366. A scheduler, which would be understood by one skilledin the art, is coupled to the processing unit 1350. The scheduler couldbe included within or operated separately from the base station 1370.The processing unit 1350 implements various processing operations of thebase station 1370, such as signal coding, data processing, powercontrol, input/output processing, or any other functionality. Theprocessing unit 1350 can also support the methods and teachingsdescribed in more detail above. Each processing unit 1350 includes anysuitable processing or computing device configured to perform one ormore operations. Each processing unit 1350 could, for example, include amicroprocessor, microcontroller, digital signal processor, fieldprogrammable gate array, or application specific integrated circuit.

Each transceiver 1352 includes any suitable structure for generatingsignals for wireless or wired transmission to one or more EDs or otherdevices. Each transceiver 1352 further includes any suitable structurefor processing signals received wirelessly or by wire from one or moreEDs or other devices. Although shown combined as a transceiver 1352, atransmitter and a receiver could be separate components. Each antenna1356 includes any suitable structure for transmitting or receivingwireless or wired signals. While a common antenna 1356 is shown here asbeing coupled to the transceiver 1352, one or more antennas 1356 couldbe coupled to the transceiver(s) 1352, allowing separate antennas 1356to be coupled to the transmitter and the receiver if equipped asseparate components. Each memory 1358 includes any suitable volatile ornon-volatile storage and retrieval device(s). Each input/output device1366 facilitates interaction with a user or other devices (networkcommunications) in the network. Each input/output device 1366 includesany suitable structure for providing information to orreceiving/providing information from a user, including network interfacecommunications.

FIG. 14 is a block diagram of a computing system 1400 that may be usedfor implementing the devices and methods disclosed herein. For example,the computing system can be any entity of UE, access network (AN),mobility management (MM), session management (SM), user plane gateway(UPGW), or access stratum (AS). Specific devices may utilize all of thecomponents shown or only a subset of the components, and levels ofintegration may vary from device to device. Furthermore, a device maycontain multiple instances of a component, such as multiple processingunits, processors, memories, transmitters, receivers, etc. The computingsystem 1400 includes a processing unit 1402. The processing unitincludes a central processing unit (CPU) 1414, memory 1408, and mayfurther include a mass storage device 1404, a video adapter 1410, and anI/O interface 1412 connected to a bus 1420.

The bus 1420 may be one or more of any type of several bus architecturesincluding a memory bus or memory controller, a peripheral bus, or avideo bus. The CPU 1414 may comprise any type of electronic dataprocessor. The memory 1408 may comprise any type of non-transitorysystem memory such as static random access memory (SRAM), dynamic randomaccess memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM),or a combination thereof. In an embodiment, the memory 1408 may includeROM for use at boot-up, and DRAM for program and data storage for usewhile executing programs.

The mass storage 1404 may comprise any type of non-transitory storagedevice configured to store data, programs, and other information and tomake the data, programs, and other information accessible via the bus1420. The mass storage 1404 may comprise, for example, one or more of asolid state drive, hard disk drive, a magnetic disk drive, or an opticaldisk drive.

The video adapter 1410 and the I/O interface 1412 provide interfaces tocouple external input and output devices to the processing unit 1402. Asillustrated, examples of input and output devices include a display 1418coupled to the video adapter 1410 and a mouse, keyboard, or printer 1416coupled to the I/O interface 1412. Other devices may be coupled to theprocessing unit 1402, and additional or fewer interface cards may beutilized. For example, a serial interface such as Universal Serial Bus(USB) (not shown) may be used to provide an interface for an externaldevice.

The processing unit 1402 also includes one or more network interfaces1406, which may comprise wired links, such as an Ethernet cable, orwireless links to access nodes or different networks. The networkinterfaces 1406 allow the processing unit 1402 to communicate withremote units via the networks. For example, the network interfaces 1406may provide wireless communication via one or more transmitters/transmitantennas and one or more receivers/receive antennas. In an embodiment,the processing unit 1402 is coupled to a local-area network 1422 or awide-area network for data processing and communications with remotedevices, such as other processing units, the Internet, or remote storagefacilities.

FIG. 15 illustrates a block diagram of an example embodiment processingsystem 1500 for performing methods described herein, which may beinstalled in a host device. As shown, the processing system 1500includes a processor 1504, a memory 1506, and interfaces 1510-1514,which may (or may not) be arranged as shown in FIG. 15 . The processor1504 may be any component or collection of components adapted to performcomputations and/or other processing related tasks, and the memory 1506may be any component or collection of components adapted to storeprogramming and/or instructions for execution by the processor 1504. Inan example embodiment, the memory 1506 includes a non-transitorycomputer readable medium. The interfaces 1510, 1512, 1514 may be anycomponent or collection of components that allow the processing system1500 to communicate with other devices/components and/or a user. Forexample, one or more of the interfaces 1510, 1512, 1514 may be adaptedto communicate data, control, or management messages from the processor1504 to applications installed on the host device and/or a remotedevice. As another example, one or more of the interfaces 1510, 1512,1514 may be adapted to allow a user or user device (e.g., personalcomputer (PC), etc.) to interact/communicate with the processing system1100. The processing system 1500 may include additional components notdepicted in FIG. 15 , such as long term storage (e.g., non-volatilememory, etc.).

In some example embodiments, the processing system 1500 is included in anetwork device that is accessing, or part otherwise of, atelecommunications network. In one example, the processing system 1500is in a network-side device in a wireless or wireline telecommunicationsnetwork, such as a base station, a relay station, a scheduler, acontroller, a gateway, a router, an applications server, or any otherdevice in the telecommunications network. In other example embodiments,the processing system 1500 is in a user-side device accessing a wirelessor wireline telecommunications network, such as a mobile station, a UE,a PC, a tablet, a wearable communications device (e.g., a smartwatch,etc.), or any other device adapted to access a telecommunicationsnetwork.

In some example embodiments, one or more of the interfaces 1510, 1512,1514 connects the processing system 1500 to a transceiver adapted totransmit and receive signaling over the telecommunications network. FIG.16 illustrates a block diagram of a transceiver 1600 adapted to transmitand receive signaling over a telecommunications network. The transceiver1600 may be installed in a host device. As shown, the transceiver 1600comprises a network-side interface 1602, a coupler 1604, a transmitter1606, a receiver 1608, a signal processor 1610, and a device-sideinterface 1612. The network-side interface 1602 may include anycomponent or collection of components adapted to transmit or receivesignaling over a wireless or wireline telecommunications network. Thecoupler 1604 may include any component or collection of componentsadapted to facilitate bi-directional communication over the network-sideinterface 1602. The transmitter 1606 may include any component orcollection of components (e.g., up-converter, power amplifier, etc.)adapted to convert a baseband signal into a modulated carrier signalsuitable for transmission over the network-side interface 1602. Thereceiver 1608 may include any component or collection of components(e.g., down-converter, low noise amplifier, etc.) adapted to convert acarrier signal received over the network-side interface 1602 into abaseband signal. The signal processor 1610 may include any component orcollection of components adapted to convert a baseband signal into adata signal suitable for communication over the device-side interface(s)1612, or vice-versa. The device-side interface(s) 1612 may include anycomponent or collection of components adapted to communicatedata-signals between the signal processor 1210 and components within thehost device (e.g., the processing system 1100, local area network (LAN)ports, etc.).

The transceiver 1600 may transmit and receive signaling over any type ofcommunications medium. In some example embodiments, the transceiver 1600transmits and receives signaling over a wireless medium. For example,the transceiver 1600 may be a wireless transceiver adapted tocommunicate in accordance with a wireless telecommunications protocol,such as a cellular protocol (e.g., LTE, etc.), a WLAN protocol (e.g.,Wi-Fi, etc.), or any other type of wireless protocol (e.g., Bluetooth,near field communication (NFC), etc.). In such example embodiments, thenetwork-side interface 1602 comprises one or more antenna/radiatingelements. For example, the network-side interface 1602 may include asingle antenna, multiple separate antennas, or a multi-antenna arrayconfigured for multi-layer communication, e.g., single input multipleoutput (SIMO), multiple input single output (MISO), multiple inputmultiple output (MIMO), etc. In other example embodiments, thetransceiver 1600 transmits and receives signaling over a wirelinemedium, e.g., twisted-pair cable, coaxial cable, optical fiber, etc.Specific processing systems and/or transceivers may utilize all of thecomponents shown, or only a subset of the components, and levels ofintegration may vary from device to device.

FIGS. 17A and 17B illustrate polarization orientations in a LOS pathpropagation 235 between a gNB 110 and a UE 120, such as a mobile phone.Each of them has two antenna-resources radiating EM waves withorthogonal polarization orientations in their Local Coordinate Systems(LCS), 1711 respectively 1721. The orthogonality of the polarizationsremains in all radiated directions. The orthogonality is also preservedif the field-vectors are transformed to the wave's plane 1730 in theglobal coordinate system (GCS) 310. The field-vectors are scaled by theantenna pattern 1710 respectively 1720, in the spherical or spatialdirection of the LOS path, given by the elevation angle θ and azimuthangle ϕ in the GCS 310.

The transmitted field-vector F_(txs)(ϕ_(ZOD), θ_(AOD)) in the GCS withpolarization orientation s, given by

${F_{{tx},s}\left( {\theta_{ZOD},\varphi_{AOD}} \right)} = {{\Psi_{tx}{F_{{tx},s}^{\prime}\left( {\theta_{ZOD}^{\prime},\varphi_{AOD}^{\prime}} \right)}} = {\Psi_{tx}\begin{bmatrix}{F_{{tx},s,\theta^{\prime}}^{\prime}\left( {\theta_{ZOD}^{\prime},\varphi_{AOD}^{\prime}} \right)} \\{F_{{tx},s,\varphi^{\prime}}^{\prime}\left( {\theta_{ZOD}^{\prime},\varphi_{AOD}^{\prime}} \right)}\end{bmatrix}}}$

with coordinate transformation given by the three rotation angles (α, β,γ)

$\Psi_{tx} = \begin{bmatrix}{\cos\left( \psi_{tx} \right)} & {- {\sin\left( \psi_{tx} \right)}} \\{\sin\left( \psi_{tx} \right)} & {\cos\left( \psi_{tx} \right)}\end{bmatrix}$ andψ_(tx) = ψ(α, β, γ, θ, ϕ)

will propagate either via a LOS or NLOS path. The rotation angles (α, β,γ) describe a rotation around the x,y, and respectively z axis to theLCS axis x′, y′, and respectively z′. If the propagation is via a NLOSpath, a scattering at an object will change the field-vectorF_(txs)(ϕ_(ZOD), θ_(AOD)) of the incident wave and emits a scatteredwave in which the 2D field-vector is transformed by the complex-valued2×2 scattering matrix S to the field-vector of the emitted wave,

${F_{{rx},{txs}}\left( {\phi_{AOD},\theta_{ZOD}} \right)} = {{S\begin{bmatrix}{F_{{txs},\theta}\left( {\theta_{ZOD},\varphi_{AOD}} \right)} \\{F_{{txs},\varphi}\left( {\theta_{ZOD},\varphi_{AOD}} \right)}\end{bmatrix}}.}$

The scattering matrix is given by arbitrary complex numbers s₁₁, s₂₁,s₂₂, s₁₂ as

$S = \begin{bmatrix}s_{11} & s_{21} \\s_{12} & s_{22}\end{bmatrix}$

Hence, S might change field vector by rotation, mirroring, scaling inmagnitude and phase changes due to the interaction with an object 1731in a NLOS propagation, see FIG. 17B. This will result in adepolarization or a change of the polarization magnitude and orientationof the scattered wave.

The projection onto the receive polarizations F_(rxu), is the receptionof the EM wave F_(rx,txs)((ϕ_(AOD), θ_(ZOD)) with the receivers uthpolarization-orientation

$\begin{matrix}{H_{{rxu},{txs}} = {\begin{bmatrix}{F_{{rxu},\theta}\left( {\theta_{1,{ZOA}},\varphi_{1,{AOA}}} \right)} \\{F_{{rxu},\varphi}\left( {\theta_{1,{ZOA}},\varphi_{1,{AOA}}} \right)}\end{bmatrix}^{T}{S\begin{bmatrix}{F_{{txs},\theta}\left( {\theta_{1,{ZOD}},\varphi_{1,{AOD}}} \right)} \\{F_{{txs},\varphi}\left( {\theta_{1,{ZOD}},\varphi_{1,{AOD}}} \right)}\end{bmatrix}}}} & (1)\end{matrix}$

and called the channel response on this path via transmit antenna s andreceive antenna u. All path attenuation and phases are described by thescattering matrix S. Since the antenna patterns are not isotropic, thefield-vector will have a different gain in each spherical direction.Since the direction is not known in general, the receiver observestransformed field-vectors in its Local Coordinate System (LCS).Expressing all filed vectors in (1) in their LCSs we get

$H_{{rxu},{txs}} = {{\begin{bmatrix}{F_{{rxu},\theta^{''}}^{''}\left( {\theta_{1,{ZOA}}^{''},\varphi_{1,{AOA}}^{''}} \right)} \\{F_{{rxu},\varphi^{''}}^{''}\left( {\theta_{1,{ZOA}}^{''},\varphi_{1,{AOA}}^{''}} \right)}\end{bmatrix}^{T}\Psi_{rx}^{T}S{\Psi_{tx}\begin{bmatrix}{F_{{tx},s,\theta^{\prime}}^{\prime}\left( {\theta_{1,{ZOD}}^{\prime},\varphi_{1,{AOD}}^{\prime}} \right)} \\{F_{{txs},\varphi^{\prime}}^{\prime}\left( {\theta_{1,{ZOD}}^{\prime},\varphi_{1,{AOD}}^{\prime}} \right)}\end{bmatrix}}} = {F_{{rxu},}^{''T}F_{{rx},{txs}}^{''}}}$

If the propagation is via a LOS path, then the scattering matrix becomes

$S = {\begin{bmatrix}1 & 0 \\1 & {- 1}\end{bmatrix}.}$

This will flip the horizontal component θ_ since the LCS of receiver1721 and transmitter 1711 are facing each other in a LOS orientation,see FIG. 17A. This is justified, since in general antennas have adirectional characteristic, such as beams, see FIGS. 17A and 17B.

FIGS. 18A-C illustrate the electric field-vectors also called phasors,of the electromagnetic waves in the far-field at a given spherical(spatial) direction and moment in time. The field-vectors can berepresented by 2D vectors F which are in the plane orthogonal to thewave direction k=k(ϕ, θ) in the GCS, see also 1730 FIG. 17A-B. Hence, itis sufficient to reduce the polarization of each EM wave to the phasorF.

In FIG. 18A, up to S field-vectors F_(tx1)′, . . . , F_(txS)′ of thetransmitted RSs 1810 in the transmitters Local Coordinate System (LCS)1711 are illustrated. Each of the S polarization orientations(field-vectors), can be sorted by the angular distance to the firstfield-vector F_(tx1)′, and is measured by the angle Ω₁ ^(t), . . . ,Ω_(S-1) ^(t) in 1812. The transmission order is clockwise if Ω₁ ^(t)≤ .. . ≤Ω_(S-1) ^(t) and anti-clockwise if Ω₁ ^(t)≥ . . . ≥Ω_(S-1) ^(t).

In FIG. 18B, up to U field-vectors F_(rx1)″, . . . , F_(rxU)″ 1801 ofthe receiver 120 in its LCS 1721 are illustrated. The angular distanceto the first field-vector F_(rx1)″ is measured by the angles Ω₁′ . . .Ω_(U-1).

In FIG. 18C, shows the received transmitted field-vectors 1811 and thereceiver's field-vectors 1801 in the receivers LCS 1721. 1811 refers tothe received S field-vectors F_(rx1)″, . . . , F_(rxS)″ of thetransmitted RSs 1810 from FIG. 18A arriving at the spherical directiongiven by the zenith angle of arrival θ″_(ZOA) and the azimuth angle ofarrival φ″_(AOA) in the received LCS 1721. The field-vectors are alwaysorthogonal to the wave's propagation direction, see 1730 in FIG. 17 .The received transmitted field-vectors F_(rx,s)″=F_(rx,txs)″ for u=1, .. . , S of a linear polarized wave can therefore be described in thewave's plane by their angular orientations and magnitude. The receivedfield-vectors via a LOS path will have the same angular separation asthe transmitted field-vectors in FIG. 18A and are measured by the sameangular distance Ω₁, . . . , Ω_(S-1) 1812 from the first receivedpolarization orientation F_(rx,1)″ The received transmittedfield-vectors F_(rx,u)″ will have different angular distances to thereceivers field-vectors F_(rxs)″, since the transmitters LCS 1711 andreceivers LCS 1721 are not aligned. The projection of the received sthtransmitted field-vector to the uth received field vector is given bythe magnitudes of the first channel tap defined in (1) and denoted by|H_(u,s)|=|H_(rxu,txs)|. The received sth transmitted field-vector'smagnitude can therefore be expressed by

${❘F_{{rx},{txs}}^{''}❘} = {\begin{bmatrix}{{❘H_{u,s}❘}/{❘F_{rxu}^{''}❘}} \\{{❘H_{u^{\prime},s}❘}/{❘F_{{rxu}^{\prime}}^{''}❘}}\end{bmatrix}.}$

if F_(rxu)″ and F_(rxu′)″ are orthogonal. Note, that the CIR taps in (1)need to be divided by the receiver's magnitude to obtain a projectiononto the normalized orthogonal vectors F_(rxu)″/|F_(rxu)″| respectivelyF_(rxu′)″/|F_(rxu′)″|, also called polarization vectors, which form anorthonormal system for the 2D polarization plane of the arriving EMwave. In more general, the ratio of two normalized projectionscorrespond to the angles α_(u,s) in FIG. 18C and are given by

$\begin{matrix}{{\alpha_{u,s} = {{atan}a_{u,u}}},\frac{❘H_{u,s}❘}{❘H_{u^{\prime},s}❘},} & (2)\end{matrix}$

for any F_(rxu′)″ which is orthogonal to F_(rxu)″.

In one embodiment, it holds U=2=S and Ω₁ ^(t)=Ω₁=Ω′₁=90° as illustratedin FIG. 19A. Without loss of generality, the orientation 1 is chosen asthe vertical orientation, aligned with the LCS z-axis and theorientation 2 is selected as the horizontal orientation, aligned withthe LCS y-axis. The following notation is used in the FIG. 19A,|H_(rxV,rxV)|=|H_(1,1)|, |H_(rxH,rxV)|=|H_(2,1)|,|H_(rxV,rxH)|=|H_(1,2)|, and |H_(rxH,rxH)|=|H_(2,2)|. The angulardistances with respect to F₁″ are then given by

$\alpha_{n} = {\alpha_{1,n} = {{{atan}a\frac{❘H_{2,n}❘}{❘H_{1,n}❘}{for}n} = {1,2}}}$

and with respect to F₂″ by

${\beta_{n} = {\alpha_{2,n} = {{{atan}a^{- 1}\frac{❘H_{1,n}❘}{❘H_{2,n}❘}{for}n} = 1}}},2,$

where the projection-ratios both had to be scaled by the receivers'magnitude ratio a=a_(1,2)=|F_(rx1)″|/|F_(rx2)″, see FIG. 18 . For a LOSpath it must then hold for n=1,2:

α_(n)+β_(n) mod 180°=Ω₁,

which is equivalent to

α₁+α₂=Ω₁ and β₁+β₂=Ω₁.  (3)

This can be also expressed more compact as

$\begin{matrix}{{d(H)} = {{d_{angle}\left( {H_{1,1},H_{1,2},H_{2,1},H_{2,2}} \right)} = {{❘{{{atan}a\frac{❘H_{1,1}❘}{❘H_{2,1}❘}} - {{atan}a^{- 1}\frac{❘H_{2,2}❘}{❘H_{1,2}❘}}}❘} \cdot \frac{2}{\pi}}}} & (4)\end{matrix}$

Note, that both conditions in (3) are equivalent to (4). If the receiveris power-balanced, i.e., 1, then one gets

$\begin{matrix}{a = {{d(H)} = {{d_{angle}\left( {H_{1,1},H_{1,2},H_{2,1},H_{2,2}} \right)} = {{❘{{{atan}\frac{❘H_{1,1}❘}{❘H_{2,1}❘}} - {{atan}\frac{❘H_{2,2}❘}{❘H_{1,2}❘}}}❘} \cdot {\frac{2}{\pi}.}}}}} & (5)\end{matrix}$

In another embodiment, the decision metric is given by a power distance,given by

$\begin{matrix}{{d(H)} = {{d_{power}\left( {H_{1,1},H_{1,2},H_{2,1},H_{2,2}} \right)} = {{❘\frac{{❘H_{2,1}❘}^{2} + {❘H_{2,2}❘}^{2} - {❘H_{1,1}❘}^{2} - {❘H_{1,2}❘}^{2}}{\max\left( {{{❘H_{2,1}❘}^{2} + {❘H_{2,2}❘}^{2}},{{❘H_{1,1}❘}^{2} + {❘H_{1,2}❘}^{2}}} \right.}❘}.}}} & (6)\end{matrix}$

In one embodiment of the invention, the transmitter and receiver angularseparation is Ω₁=90° and the receiver is power-balanced with a=1.

In one embodiment of the invention, the angle and power distance can becombined. Here, the two different thresholds can be relaxed, and adecision for LOS would be concluded if both metrics conditions hold.

FIG. 19B illustrates the field-vectors in the wave's plane for a givenspherical direction, for a general LOS polarization procedure for areceiver with only one polarization orientation, i.e., U=1. Thetransmitter will transmit a plurality of RS via S=N differentpolarization orientations, given by the angles Ω₁, . . . , Ω_(S-1)measured relative to the transmitters first polarization orientationF_(tx1)″ 1911. All transmitted polarization orientations are inincreasing order of their angles Ω₁≤ . . . ≤Ω_(S-1), known by thetransmitter. In one embodiment, where the receiver is making the LOScharacterization, the angles of the transmitted polarizationorientations needs to be known also by the receiver. In one embodiment,the receiver observes all S different RSs by U receiver polarizationorientations, with angular separations Ω′₁≤ . . . ≥Ω′_(U-1). In oneembodiment, the receiver observers only with U=1 receiver polarizationorientation F_(rx)″, pictured by the dashed purple arrow 1901.

FIG. 19B illustrates the transmit polarization orientations in thetransmitters LCS 1921. The polarization orientations are measured by theangles Ω₁ ^(t)≤ . . . ≤Ω^(t) _(S-1), from the first polarizationorientation F_(tx1)′ in the transmitter LCS. A metric d will depend onall magnitudes from the first received channel taps |H₁|, . . . ,|H_(N)|.

In FIGS. 20A-C, a signaling procedure is illustrated which uses fourpolarization orientations, given by an angular separations of

$\frac{\pi}{4} = {45{^\circ}}$

which corresponds to the angles Ω₁=45°, Ω₂=90°, and Ω₃=135°, measuredfrom the first transmitted polarization orientation F_(txV)′=F_(tx1)′1810 in FIG. 18A. All four polarization signals will be measured by asingle receiver orientation F_(rx1)″=F″_(x) which is given by theintensities (magnitudes) of the first received channel tap|H_(n)|=|H_(rxV,txn)|. In one embodiment, a LOS decision is made byevaluating the metric

${{d(H)} = {{d_{4}\left( {H_{1},\ldots,H_{4}} \right)} = {❘{\frac{❘H_{i_{3}}❘}{❘H_{i_{2}}❘} - \frac{{❘H_{i_{1}}❘} - {❘H_{i_{4}}❘}}{{❘H_{i_{1}}❘} + {❘H_{i_{4}}❘}}}❘}}},$

where the measured first channel tap magnitudes are sorted in decreasingorder |H_(i) ₁ |≥ . . . ≥|H_(i) ₄ |.

FIG. 20D illustrates a signaling procedure with only three transmitpolarization orientations and a singular receive polarizationorientation. In one embodiment, the metric would be

${d(H)} = {{d_{3}\left( {H_{1},\ldots,H_{3}} \right)} = {\frac{4}{3\pi}\left\{ \begin{matrix}{{❘{{{arcos}\frac{❘H_{3}❘}{c}} - {{arcos}\frac{❘H_{2}❘}{c}} - \frac{\pi}{4}}❘},} & {{❘H_{1}❘} < {❘H_{3}❘}} \\{{❘{{{arcos}\frac{❘H_{1}❘}{c}} + {{arcos}\frac{❘H_{2}❘}{c}} - \frac{\pi}{4}}❘},} & {else}\end{matrix} \right.}}$

where c=√{square root over (|H₁|²+|H₃|²)}. The metric requires theknowledge of the transmit polarization order. In all polarization-LOSprocedures, the threshold ρ for the LOS decision will depend on otherparameters, such as the received signal-to-noise-ratio (SNR), the RiceanK-factor, the clutter density of the scenario.

For each of the above normalized metrics d, a certain fixed threshold1>ρ>0, must be chosen. If the metric satisfies d(H)<p, then thedetection algorithm decides for a LOS path and otherwise for a NLOSpath. In one embodiment, the power based metric d_(power) and anglebased metric d_(angle) can be combined, such that the combined detectionalgorithm decides for a LOS path if d_(angle)(H)<ρ_(angle,c) andd_(power)(H)<ρ_(power,c) holds. Here ρ_(angle,c) and ρ_(power,c) couldbe relaxed thresholds given by some scaling factors c_(angle),c_(power)>1

ρ_(angle,c) =c _(angle)ρ_(angle) and ρ_(power,c) =c _(power)ρ_(power).

Furthermore, the thresholds might depend on the SNR at the receiver andthe a priori LOS probability to be expected, or any other a prioriinformation. For example by

${\rho({SNR})} = {{\rho_{angle}({SNR})} = {\min\left\{ {\rho_{\max},{\rho_{\min} + \frac{1}{2 \cdot {SNR}}}} \right\}}}$

where SNR is on the FAP of each link, derived by the average RSRP overall received polarizations and the observed noise-floor at the receiver.A large threshold would lead to not enough NLOS elimination for theangle-based metric, and therefore a maximum threshold of ρ_(max)=0.5 isadopted. This maximal threshold might be further optimized depending onthe LOS statistics of the scenario. Furthermore, a minimal thresholdρ_(min) can be used to adjust for a fixed bias or offset in the decisionmetric. This is due to the fact, that the channel distortion itself,will result in a metric larger than zero. The true LOS path might stillbe distorted by interference or other nearby NLOS paths which result inan offset of the metrics value for the LOS case.

In another embodiment, the transmitter can transmit more than S>4different polarization orientations, as illustrated in FIG. 20E. Assumethe transmitter sends the PRS signals over S polarization orientationsseparated and ordered anti-clockwise by Ω≤Ω₁ ^(t)≤ . . . ≤Ω^(t) _(S-1)which will be observed at the receiver in clockwise order, see FIG. 20E.The receiver can measure the angular distance α_(1,s) with (2) for s=1,. . . , S from its first polarization orientation F_(rx1)″ if U=2. IfU=1 and the transmitted polarizations are power-balanced, the receivercan scale the measurements |H_(S)|=|H_(rx1,txs)| by the largest value|H_(M)| for some M, and can approximate the angles by

${\alpha_{s} = {{{acos}\frac{❘H_{1,s}❘}{❘H_{1,M}❘}{for}s} = 1}},2,\ldots,{S.}$

The approximation error |α_(1,s)−α_(s)| will decrease if S increases.The transmitted relative angular distances are uniform spread over thefirst quadrant I, i.e,

$\hat{S} = \left\{ {\begin{matrix}\frac{S - 1}{2} & {,{S{odd}}} \\{\frac{S}{2} + 1} & {,{S{even}}}\end{matrix}.} \right.$

Let us define the middle angular index by

${{❘{\Omega_{s + 1}^{t} - \Omega_{s}^{t}}❘} = {{\frac{\pi}{2\left( {S - 1} \right)}{for}s} = 1}},\ldots,{S - 1.}$

The receiver identifies first if the first received polarizationF_(rx,tx1)″ is located in quadrant I/III or quadrant II/IV in FIG. 20E.If

${\alpha_{\hat{S}} < {\frac{\pi}{4} - \frac{\left( {\hat{S} - \frac{S + 1}{2}} \right)\pi}{2\left( {S - 1} \right)}}},$

then the first received polarization correspond to the case in quadrantII/IV, otherwise to quadrant I/III. This defines the index at which theangles need to switch sign

$M = \left\{ {\begin{matrix}{\min\left\{ {{\hat{S} + \left\lfloor \frac{2\left( {S - 1} \right)\alpha_{\hat{S}}}{\pi} \right\rfloor},{S - 1}} \right\}} & {,{\alpha_{\hat{S}} < {\frac{\pi}{4} - \frac{\left( {\hat{S} - \frac{S + 1}{2}} \right)\pi}{2\left( {S - 1} \right)}}}} \\{\min\left\{ {{1 + \left\lfloor \frac{2\left( {S - 1} \right)\alpha_{\hat{S}}}{\pi} \right\rfloor},\hat{S}} \right\}} & {,{else}}\end{matrix},} \right.$

where └α┘ denotes the smallest integer n>α. The decision metric is thengiven by

$\begin{matrix}{{d(H)} = {{d_{{angle},S}\left( {❘H_{u,s}❘} \right)} = {\frac{2}{\left( {S - 1} \right)\pi}{❘{\frac{\pi}{2} - \left( {❘{\alpha_{M} + {\alpha_{M + 1}{❘{+ {\sum\limits_{{s = 1},{s \neq M}}^{S - 1}{❘{\alpha_{s} - \alpha_{s + 1}}❘}}}}}}} \right)}❘}}}} & (7)\end{matrix}$

For S=2 this simplifies to (5). Depending on S a normalization factorc(S) can be found such that

$\frac{d_{{angle},S}\left( {❘H_{u,s}❘} \right)}{c(S)} \in {\left\lbrack {0,1} \right\rbrack.}$

An optimized threshold ρ_(angle,S) can be designed depending on S, theLOS probability, the SNR, and the statistic of the scattering matrix, todecide for LOS or NLOS path as described above.

FIG. 21A illustrates a block diagram for a Polarization-LOScharacterization. The receiver, such as a UE, is requesting a Pol-LOSprocedure from one or multiple transmitters, which will transmitequal-power RSs over a plurality of different polarization orientations.The UE needs to know the polarization signaling scheme in order toselect the correct metric d to make in 2114 a decision for LOS or NLOS.The result will be reported back to the transmitter in 2116. The resultcan be binary (hard-value) or a numeric value (soft-value).

FIG. 21B illustrates a block diagram for taking polarization LOSmeasurements by a receiver 204. The receiver will report back themeasurements. In one embodiment, the receiver only may report back theRSRP sequence of the FAP.

In one embodiment, the UE may perform the LOS determination on its own,without being probed by the network, as illustrated in FIG. 22 . If theUE knows or can identify the polarization orientations in the RSsequence 2202 by step 2206, the above metrics allow a UE-based LOSdecision in 2114. This can be referred as UE-based LOS determination.The signaling to implement this solution is described below. Note thatthe signaling is not UE-based specific and may be used for network-basedsolution as well. For that purpose, the existing positioning SIB may beused. More specifically, the Information Element (IE) SIBPos as definedin TS38.331 and shown below may be used:

-- ASN1START -- TAG-SIPOS-START SIBpos-r16 : := SEQUENCE {  assistanceDataSIB-Element-r16 OCTET STRING,   lateNonCriticalExtensionOCTET STRING OPTIONAL,   . . . } -- TAG-SIPOS-STOP -- ASN1STOP

The field assistanceDataSIB-Element (release suffix omitted) isdescribed as follows in TS37-355:

AssistanceDataSIBelement-r15 : := SEQUENCE {     valueTag-r15 INTEGER(0..63) OPTIONAL,     expirationTime-r15 UTCTime OPTIONAL,    cipheringKeyData-r15 CipheringKeyData-r15 OPTIONAL,    segmentationInfo-r15 SegmentationInfo-r15 OPTIONAL,    assistanceDataElement-r15 OCTET STRING, . . . }

The field assistanceDataElement is defined as follows:

assistanceDataElement The assistanceDataElement OCTET STRING depends onthe posSibType and is specified in Table 7.2-1. NOTE.

For Table, 7.2-1, new rows are added to indicate the UE-based LOSdetermination (new rows highlighted):

TABLE 7.2-1 Mapping of posSibType to assistanceDataElement posSibTypeassistanceDataElement GNSS Common Assistance posSibType1-1GNSS-Reference Time Data (clause 6.5.2.2) posSibType1-2GNSS-ReferenceLocation posSibType1-3 GNSS-IonosphericModel posSibType1-4GNSS-EarthOrientationParameters posSibType1-5GNSS-RTK-ReferenceStationInfo posSibType1-6GNSS-RTK-CommonObservationInfo posSibType1-7GNSS-RTK-AuxiliaryStationData posSibType1-8 GNSS-SSR-CorrectionPointsGNSS Generic Assistance posSibType2-1 GNSS-TimeModelList Data (clause6.5.2.2) posSibType2-2 GNSS-DifferentialCorrections posSibType2-3GNSS-NavigationModel posSibType2-4 GNSS-RealTimeIntegrity posSibType2-5GNSS-DataBitAssistance posSibType2-6 GNSS-AcquisitionAssistanceposSibType2-7 GNSS-Almanac posSibType2-8 GNSS-UTC-Model posSibType2-9GNSS-AuxiliaryInformation posSibType2-10 BDS-DifferentialCorrectionsposSibType2-11 BDS-GridModelParameter posSibType2-12GNSS-RTK-Observations posSibType2-13 GLO-RTK-BiasInformationposSibType2-14 GNSS-RTK-MAC-CorrectionDifferences posSibType2-15GNSS-RTK-Residuals posSibType2-16 GNSS-RTK-FKP-Gradients posSibType2-17GNSS-SSR-OrbitCorrections posSibType2-18 GNSS-SSR-ClockCorrectionsposSibType2-19 GNSS-SSR-CodeBias posSibType2-20 GNSS-SSR-URAposSibType2-21 GNSS-SSR-PhaseBias posSibType2-22GNSS-SSR-STEC-Correction posSibType2-23 GNSS-SSR-GriddedCorrectionposSibType2-24 NavIC-DifferentialCorrections posSibType2-25NavIC-GridModelParameter OTDOA Assistance Data posSibType3-1OTDOA-UE-Assisted (clause 7.4.2) Barometric Assistance DataposSibType4-1 Sensor-AssistanceDataList (clause 6.5.5.8) TBS AssistanceData posSibType5-1 TBS-AssistanceDataList (clause 6.5.4.8) NRDL-TDOA/DL-AOD posSibType6-1 NR-DL-PRS-AssistanceData Assistance Data(clauses posSibType6-2 NR-UEB-TRP-LocationData 6.4.3, 7.4.2)posSibType6-3 NR-UEB-TRP-RTD-Info NR LOS Assistance Data posSibTypeX-YNR-TRP-LOSAssistanceData

In one embodiment, a new SIB type is defined to indicate the PRSlocation for both (or more) polarizations. The IENR-DL-PRS-LOSAssistanceData is used by the location server to provideDL-PRS assistance data.

An IE called NR-TRP-LOS-AssistanceData is defined. An exemplarydescription is given below (omitting release suffix and using fieldsnames/types as defined in TS37.355).

NR-TRP-LOS-AssistanceData ::= SEQUENCE {     nr-DL-PRS-ReferenceInfoDL-PRS-ID-Info,     nr-DL-PRS-AssistanceDataList-Hor SEQUENCE (SIZE (1..nrMaxFreqLayers) ) OF NR-DL-PRS- AssistanceDataPerFreq,    nr-DL-PRS-AssistanceDataList-Ver SEQUENCE (SIZE (1..nrMaxFreqLayers) ) OF NR-DL-PRS- AssistanceDataPerFreq,    nr-SSB-Config SEQUENCE (SIZE (1. .nrMaxTRPs) ) OF NR-SSB-Config    OPTIONAL,  -- Need ON     . . . } NR-DL-PRS-AssistanceDataPerFreq::= SEQUENCE {     nr-DL-PRS-PositioningFrequencyLayer    NR-DL-PRS-PositioningFrequencyLayer,    nr-DL-PRS-AssistanceDataPerFreq SEQUENCE (SIZE (1..nrMaxTRPsPerFreq) ) OF NR-DL-PRS- AssistanceDataPerTRP,     . . . }NR-DL-PRS-AssistanceDataPerTRP ::= SEQUENCE {     dl-PRS-ID INTEGER (0..255),     nr-PhysCellID OPTIONAL,   -- Need ON     nr-CellGlobalID NCGI    OPTIONAL,  -- Need ON     nr-ARFCN ARFCN-ValueNR     OPTIONAL,  --Cond NotSameAsRefServ     nr-DL-PRS-SFNO-Offset NR-DL-PRS-SFNO-Offset,    nr-DL-PRS-expectedRSTD INTEGER (−3841..3841),    nr-DL-PRS-expectedRSTD-uncertainty     . . . }

Another way to represent the information elementNR-TRP-LOS-AssistanceData:

NR-TRP-LOS-AssistanceData ::= SEQUENCE {     nr-DL-PRS-ReferenceInfoDL-PRS-ID-Info,     nr-DL-PRS-AssistanceDataList-HorNR-DL-PRS-AssistanceData-r16,     nr-DL-PRS-AssistanceDataList-VerNR-DL-PRS-AssistanceData-r16,     . . . }

In this embodiment, NR-TRP-LOS-AssistanceData uses a structure similarto NR-DL-PRS-AssistanceData, but with two sequences of PRS: one for thehorizontal polarization, one for the vertical polarization. Otherembodiments using a slightly different signaling are possible: forinstance, the differentiation between horizontal or verticalpolarization could be done in the NR-DL-PRS-AssistanceDataPerFreq IE, orin NR-DL-PRS-AssistanceDataPerTRP. One possibility, for instance, wouldbe to add a field to indicate the polarization inNR-DL-PRS-AssistanceDataPerTRP (as BOOLEAN if two polarizations, INTEGERotherwise) and modify the other IEs accordingly.

Note also that in other embodiments, the LOS determination could belinked to a single positioning technique (e.g., TDOA). In such a case,NR LOS Assistance Data could be defined as a posSIBType6-Y or could evenbe omitted and defined in NR-DL-PRS-AssistanceData modified forRelease-17 (or other) to indicate the PRSs for multiple polarization.

UE LOS/NLOS determination for multitude for PRS received from amultitude of cells may be communicated to the location server via an IEProvideLOSInformation:

-- ASN1START ProvideLOSInformation ::= SEQUENCE {   LOS-SignalMeasurementInformation LOS-SignalMeasurementInformationOPTIONAL,    LOS-Error LOS-Error OPTIONAL,    . . . } -- ASN1STOP --ASN1START LOS-SignalMeasurementInformation ::= SEQUENCE {   LOSprimaryCellMeasuredResults LOS-MeasuredResultsElement    OPTIONAL,   LOSmeasuredResultsList LOS-MeasuredResultsList,      . . . }LOS-MeasuredResultsList ::= SEQUENCE (SIZE (1. .32) ) OFLOS-MeasuredResultsElement LOS-MeasuredResultsElement ::= SEQUENCE {   physCellId    INTEGER (0. .503),    cellGlobalIdCellGlobalIdEUTRA-AndUTRA OPTIONAL,    arfcnEUTRA    ARFCN-ValueEUTRA,   systemFrameNumber BIT STRING (SIZE (10)) OPTIONAL,    LOS-Result   INTEGER (0. .97)    OPTIONAL, } -- ASN1STOP

Where LOS-Result integer represents the LOS determination where theinteger 0 means total blockage and 97 represents total LOS. In adifferent embodiment the LOS-Result may mean just the order ofpreference based on measurements with a higher number interpreted as ahigher preference.

In one embodiment, the LOS determination by a UE can be used forside-link positioning, such as for car to car radar/communication toavoid collision or track distance and speed of the nearby cars. Here,the UEs (cars) can apply the LOS determination in a wireless side-linkcommunication.

U.S. Provisional Application No. 62/738,845, filed on Sep. 28, 2018,entitled “Method for LOS Determination,” and U.S. ProvisionalApplication No. 62/746,472, filed Oct. 16, 2018, entitled “Method andApparatus for Determining Line of Sight (LOS),” are hereby incorporatedherein by reference in their entirety.

Although a combination of features is shown in the illustrated examples,not all of them need to be combined to realize the benefits of variousexample embodiments of this disclosure. In other words, a system ormethod designed according to an example embodiment of this disclosurewill not necessarily include all of the features shown in any one of theFigures or all of the portions schematically shown in the Figures.Moreover, selected features of one example embodiment may be combinedwith selected features of other example embodiments.

In some example embodiments, some or all of the functions or processesof the one or more of the devices are implemented or supported by acomputer program that is formed from computer readable program code andthat is embodied in a computer readable medium. The phrase “computerreadable program code” includes any type of computer code, includingsource code, object code, and executable code. The phrase “computerreadable medium” includes any type of medium capable of being accessedby a computer, such as read only memory (ROM), random access memory(RAM), a hard disk drive, a compact disc (CD), a digital video disc(DVD), or any other type of memory.

It may be advantageous to set forth definitions of certain words andphrases used throughout this patent document. The terms “include” and“comprise,” as well as derivatives thereof, mean inclusion withoutlimitation. The term “or” is inclusive, meaning and/or. The phrases“associated with” and “associated therewith,” as well as derivativesthereof, mean to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, or the like.

While this disclosure has described certain example embodiments andgenerally associated methods, alterations and permutations of theseexample embodiments and methods will be apparent to those skilled in theart. Accordingly, the above description of example embodiments does notdefine or constrain this disclosure. Other changes, substitutions, andalterations are also possible without departing from the spirit andscope of this disclosure, as defined by the following claims.

What is claimed is:
 1. A method, comprising: receiving, by a firstdevice from a second device, an indicator of Line of Sight (LOS) or NonLine of Sight (NLOS) feature support; communicating, by the first devicewith the second device, an LOS determination request including an LOSindicator indicating that an LOS procedure is used in LOScharacterization of a transmission between the first device and thesecond device; receiving, by the first device from the second device, afirst set of reference signals via a first plurality of resources and asecond set of reference signals via a second plurality of resources;measuring, by the first device, the first set of reference signals togenerate first measurements; measuring, by the first device, the secondset of reference signals to generate second measurements; comparing, bythe first device, the first measurements and the second measurements;determining, by the first device, a LOS propagation indicator indicatingLOS or NLOS propagation between the first device and the second devicebased on the comparing; and transmitting, by the first device to thesecond device, the LOS propagation indicator.
 2. The method of claim 1,wherein the LOS indicator is a binary indicator indicating that the LOScharacterization is LOS or NLOS.
 3. The method of claim 1, wherein theLOS indicator is a multiple level soft indicator indicating a likelihoodor confidence to which the LOS characterization is LOS or NLOS.
 4. Themethod of claim 1, the measuring the first set of reference signalscomprising: receiving, by the first device, each reference signal of thefirst set of references signals separately on each correspondingresource of the first plurality of resources; and identifying, by thefirst device, via a search procedure, the each reference signalcorresponding to the each corresponding resource.
 5. The method of claim4, the search procedure comprising a maximal correlation receiver overall possible reference signals.
 6. The method of claim 1, the first setof reference signals received over a first path of a first polarization,the second set of reference signals received over a second path of asecond polarization, the first measurements include first measuredpower, the second measurements include second measured power, thedetermining comprising: determining, by the first device, the LOSpropagation indicator based on a difference between the first measuredpower and the second measured power and based on a threshold.
 7. Themethod of claim 6, the determining comprising: determining, by the firstdevice, that the difference exceeds the threshold; and determining, bythe first device, that the LOS characterization of the transmissioncomprises a LOS transmission.
 8. The method of claim 6, furthercomprising: determining, by the first device, that the difference doesnot exceeds the threshold; and determining, by the first device, thatthe LOS characterization of the transmission comprises an NLOStransmission.
 9. The method of claim 8, further comprising:transmitting, by the first device, the LOS characterization of thetransmission.
 10. The method of claim 1, further comprising: receiving,by the first device from the second device, the LOS characterization ofthe transmission.
 11. The method of claim 1, the communicating the LOSdetermination request comprising: transmitting, by the first device, theLOS determination request or receiving the LOS determination request.12. The method of claim 1, wherein the first set of reference signalsand the second set of reference signals are received sequentially intime.
 13. A first device, comprising: at least one processor; and anon-transitory computer readable storage medium storing instructionsthat, when executed by the at least one processor, cause the firstdevice to perform operations including: receiving, from a second device,an indicator of Line of Sight (LOS) or Non Line of Sight (NLOS) featuresupport; communicating, with the second device, an LOS determinationrequest including an LOS indicator indicating that an LOS procedure isused in LOS characterization of a transmission between the first deviceand the second device; receiving, from the second device, a first set ofreference signals via a first plurality of resources and a second set ofreference signals via a second plurality of resources; measuring thefirst set of reference signals to generate first measurements; measuringthe second set of reference signals to generate second measurements;comparing the first measurements and the second measurements;determining a LOS propagation indicator indicating LOS or NLOSpropagation between the first device and the second device based on thecomparing; and transmitting, to the second device, the LOS propagationindicator.
 14. The first device of claim 13, wherein the LOS indicatoris a binary indicator indicating that the LOS characterization is LOS orNLOS.
 15. The first device of claim 13, wherein the LOS indicator is amultiple level soft indicator indicating a likelihood or confidence towhich the LOS characterization is LOS or NLOS.
 16. The first device ofclaim 13, the measuring the first set of reference signals comprising:receiving each reference signal of the first set of references signalsseparately on each corresponding resource of the first plurality ofresources; and identifying via a search procedure, the each referencesignal corresponding to the each corresponding resource.
 17. The firstdevice of claim 16, the search procedure comprising a maximalcorrelation receiver over all possible reference signals.
 18. The firstdevice of claim 13, the first set of reference signals received over afirst path of a first polarization, the second set of reference signalsreceived over a second path of a second polarization, the firstmeasurements include first measured power, the second measurementsinclude second measured power, the determining comprising: determiningthe LOS propagation indicator based on a difference between the firstmeasured power and the second measured power and based on a threshold.19. The first device of claim 18, the determining comprising:determining that the difference exceeds the threshold; and determiningthat the LOS characterization of the transmission comprises a LOStransmission.
 20. The first device of claim 18, the operations furthercomprising: determining that the difference does not exceeds thethreshold; and determining that the LOS characterization of thetransmission comprises an NLOS transmission.